Are you ready to taste the rainbow with a vibrant 6-layer cake?

Today we are whipping up a batch of my “melt in your mouth” white cake. I use this white cake as the base for so many cake recipes. It really is the PERFECT cake with a deliciously soft texture, just the right amount of wonderful vanilla flavor, and tastes like love with creamy vanilla buttercream on top.

Trust me, even if you’re not a cake person (if that type of person exists) you are going to love this Mason Jar Rainbow Cake: soft & airy, moist but not eggy, a touch of sweetness, stick to your fork tender, and an easy recipe.

Now I know homemade cakes can be a scary thing for many people. This recipe ideally skips all of the typical fuss and stress around baking a cake. A simplified cake base with a perfectly smooth vanilla buttercream frosting is all you need.

Be sure to grab the full recipe & check out the full video tutorial in the recipe card below. And if you try this recipe (I mean you totally should be), tag me on Instagram @imancake and use the hashtag #BakingWithMANCAKE.




  1. Sift and whisk dry ingredients together.
  2. Mix wet ingredients in a separate bowl.
  3. Add wet to dry mixture and mix until combined.
  4. Bake in prepared pans until centers are springy to the touch.

Use Room Temperature Ingredients

Cold ingredients do not mix well with room temperature ingredients.

As with any recipe that calls for dairy products, always be sure to take the time to bring ingredients to room temperature because it will result in a lighter, fluffier bake. 

Proper Measurements

Proper measuring of ingredients is key to perfectly baked cakes & cupcakes, especially when you are making them from scratch.

Take a moment to kneel down, get face to face with your measuring cup, and measure liquids at eye level in standard liquid measuring cups.

When it comes to dry ingredients, measure by spooning the ingredient into a measuring cup or spoon, then leveling off the top with a knife or straight edge spatula.

Don’t Overmix the Batter

No matter what you will be placing into your oven, over-mixing the batter can lead to over-developing the gluten, which means your cake or cupcakes will come out dense and heavy.

Bake Immediately

Bake your desserts immediately after mixing the batter.

Letting batter stand for too long can cause some of the air you’ve beaten in to escape, making for a denser bake.

No Peeking!

While it can be tempting, resist the urge to peek in the oven on your dessert’s progress. Opening or closing the oven door before the baking time is complete can cause fragile air bubbles in the batter to burst, preventing the bakes from rising.

Even if you are gentle with the oven door, a rush of cold air can affect the bake while it is trying to set up, resulting in dense, deflated bake. Try to resist the urge to peek until your bakes are at least 2/3 through their baking time.

How to Test if Your Baked Treats are Done

Test your bakes for doneness while they’re still in the oven by inserting a cake tester or wooden toothpick into the center.

Your bakes are done when the tester or toothpick comes out with no more than a few moist crumbs clinging to it; you should see no wet batter.

You can also gently press down on the bake and, if it bounces back leaving no dent, then it is done. If removed too early, the bake will sink in the center as it cools and, if over baked, it will be dry.


  • If you’re not using 6-inch pans, double the recipe for 8-inch pans or triple the recipe for 9-inch pans.
  • You can substitute whole milk or yogurt for sour cream if desired, I do it all the time and can’t really tell the difference.
  • Make sure to WHIP your buttercream just before using, especially if using a Meringue-base. Meringue-based frostings will loose consistency quickly and become impossible to smooth if you leave them too long.

Be sure to enter the MANCAKE KitchenAid giveaway.

I have 20 KitchenAid Stand Mixers to giveaway & one of them could be yours!



I used vanilla for this cake but you can have fun with other extracts like orange blossom water and rose water for a delicious floral note.

Oftentimes white cakes are made with artificial “almond” extract, I however am not partial to that particular flavor.


I went for a simple but charming of decoration scheme for this cake. Whipped buttercream smooths out really well as long as you remember to give it a quick whip just before using. It becomes bubbly if left on it’s own too long.

The side was smoothed with a bench scraper and I used an offset spatula for the top.


Frosting Has Bubbles: Before you pipe buttercream onto a cake try giving is a final whip JUST before you use it.

Buttercream looses it’s beautiful consistency pretty quickly, especially if it’s meringue-based like Swiss and Italian frostings.


Yes! You can stack it, wrap it in fondant if desired and scale it up to an 8 or 9 inch triple layer cake by doubling of tripling the recipe respectively.


  1. Cream the Butter: To achieve a good rise, properly cream the butter and sugar together. We have a crutch of baking powder and soda, but the recipe begins with that very first and imperative step: beating the butter and sugar together until creamy.
  2. Egg Whites: Use ONLY egg whites. No yolks. Not only will using only egg whites give us a pristine white cake, it will ensure that the crumb is not weighed down by the fat in egg yolks. Think about it: lighter confections such as marshmallows and angel food cakes only require egg whites. Same story here.
  3. Sour Cream: Sour cream is the cake’s security blanket; it keeps everything moist.
  4. Room Temperature: Make sure all of your ingredients are at room temperature. When ingredients are the same temperature, they bind together more readily than if you had some cold and some warmer ingredients. Colder ingredients, especially egg whites, will produce a thicker batter and, since it’s cold, will take longer to bake. This changes everything.

To put it lightly, make sure you’re creaming the butter and sugar together properly, all your ingredients are the same temperature, and you use egg whites, sour cream, and cake flour. The result is an ultra-light cake with buttery vanilla flavor you won’t regret – Every. Single. Time.


Baking in jars is ready-made for warm weather. You end up with perfectly contained self-serve portions ideal for toting to Pride or hauling out to the backyard on a tray. Set them out on the picnic table or buffet, let your guests do the rest.

Gather Your One-Pint Canning Jars

Start with clean, dry one-pint canning jars. Be sure to follow the washing instructions on the canning jar box. If re-using jars, be sure to use brand new lids and seals. You’ll need 6 jars for the batter of one 2-layer cake recipe. The wider the mouth of the 1-pint jars the best they will work when trying to “dump” the cake out.


Give each jar a light spritz of spray oil to give each a complete covering.


Using a baking sheet, preferably with high sides, is needed to support the canning jar cakes in and out of the oven. With using a baking sheet with tall sides, will prevent any spillage from the water bath you’ll be baking your mason jar cakes in.


Use a piping bag to add the batter to the jar. Any batter that sticks to the side, wipe out. Fill the jars to just under the 1-cup mark.


Next, bake your cake. You can use a bamboo skewer to test for doneness. 

Bake longer, if necessary.

If your cakes don’t come out exactly the same, don’t worry. Most ovens have hot spots, where one part of the oven is hotter than another. This can cause variations when baking. 

I recommend rotating the baking sheet halfway through the baking time so that the baked cakes have the opportunity to even out.

How to Store Cakes

Cakes are at their best within the first 2 days of baking. While they can last up to 5 days at room temperature in an airtight container, they will start to dry out after 3-4 days.

Be sure to let the cakes cool completely. Packing un-iced cakes while still warm can create sticky tops, making it more difficult to get the icing to stick when you are ready to frost them.

Choose an airtight container that is tall enough, so the container lid doesn’t touch the icing. Typically, the container can be left out at room temperature.

However, if you are experiencing hot and humid weather that is causing the icing to melt or if the cakes are filled or decorated with something that requires refrigeration (like lemon curd or a meringue buttercream), you can store them in the refrigerator.

If you must refrigerate your cakes, bring them back to room temperature before serving.

Freezing Baked Cakes

Un-iced cakes can be frozen for up to 3 months. Be sure the cakes are completely cooled to room temperature before freezing to avoid condensation forming, which can result in soggy cakes when it’s time to defrost them.

While simply placing the cakes in an airtight container is enough, individually wrapping each cake before placing them in the airtight container will better help preserve the freshness and taste.

After removing them from the freezer, let them defrost uncovered to prevent the tops from getting sticky.

Buttercream Tips

Butter: I almost always specify unsalted butter in my recipes then add salt back in. I do this because different manufacturers put in various amounts of salt and I don’t want anyone to make something too salty or not salted enough using my recipes. If you only have salted butter on hand go ahead and use it. You can add more salt to taste if needed.

Confectioners Sugar: Not all brands are equal and some will definitely be lumpier than others. It’s always a good idea to sift it out before using, especially if you’re using piping tips. A little lump can clog the tip and cause a big problem. 

Frequently Asked Buttercream Questions

Buttercream Starts Looking Ragged: When you’re doing the final smoothing and you notice the texture of the buttercream become a bit ragged there’s an easy fix! Get a bowl of HOT water and dip your tools in to to warm them up. pat dry and smooth. The warm metal will melt the buttercream and give you a nice SMOOTH finish.


  • For a whiter buttercream it’s really important to use a pale butter. Almost every recipe will call for using unsalted butter but then have you add salt back in. This is done because various brands of butter have different amounts of salt in their product.
  • Using unsalted butter helps to ensure a consistent result. You can however use salted butter, omit additional salt and have a delicious frosting. 
  • The most important thing to do when whipping up a batch of buttercream is that it’s room temperature!


If you need to warm some cold butter up just slice it into some smaller pieces and microwave them on a plate at 50% power for 10 second bursts.

Flip them after each burst and they’re be nice and room temperature in no time!


The main difference between buttercream and whipped frosting is butter. Whipped frosting does not contain butter and is a lighter and fluffier icing.

Buttercream contains a good amount of butter and has more of a rich flavor; so you be the judge! 🙂


When buttercream is left out at room temperature, it will form sort of a crust on the outer layer while the inside will stay fairly smooth.

If it is very warm or humid, the buttercream can loose structure. This will affect decorations you’ve pipes and may even destabilize layer cakes, causing them to sag or collapse.


You can leave out buttercream frosting for overnight if covered. If the buttercream contains cream cheese, then it should always be refrigerated for it to remain safe to eat.

Buttercream that contains dairy will spoil more quickly so should be refrigerated after a few hours.


If you want to thin out buttercream frosting, you’ll want to add in some extra cream or milk. I recommend mixing in a tablespoon at a time until the desired consistency is reached.


  • Sift your powdered sugar to avoid clogging piping tips.
  • Scrape the bowl down; to help ensure even consistency throughout.
  • You can use almost anything to flavor buttercream, fruit juice, coffee, orange blossom or rose water, melted chocolate, or Oreos!
  • If your buttercream has been sitting for a while or was chilled and brought back to room temperature it’s always a good idea to give it a quick whip to restore it’s consistency.
  • If you’re looking for a very spreadable and very smooth icing, you can add the full amount of cream in (and maybe even a bit more).

What I Use To Make Cakes

If you’ve tried this tasty treat then don’t forget to rate the recipe and let me know how you got on in the comments below, I love hearing from you!

Mason Jar Rainbow Cake

Mason Jar Rainbow Cake

Prep Time: 5 minutes
Cook Time: 30 minutes
Additional Time: 10 minutes
Total Time: 45 minutes


  • 2 1/4 cups flour
  • 2 1/4 teaspoons baking powder
  • 3/4 teaspoon salt
  • 1 stick butter at room temperature
  • 1 1/2 cup sugar
  • 1/4 cup vegetable oil
  • 5 egg whites at room temperature
  • 1 1/2 teaspoons clear vanilla
  • 1 cup whole milk at room temperature
  • 1 stick butter at room temperature
  • 1/2 cup vegetable shortening
  • 1 teaspoon vanilla
  • 4 cups powdered sugar, sifted
  • 4 tablespoons heavy cream at room temperature
  • 1 cup rainbow sprinkles
  • Food gel color (red, orange, yellow, green, blue, purple)
  • 4 wide-mouth mason jars, about 1 pint each
  • Rainbow sprinkles


  1. Preheat oven to 325 degrees.


  1. One batch will be enough to fill 4 jars. If you need to make more, simply double your batch.
  2. Whisk dry ingredients together.
  3. In another bowl, beat butter & sugar together until light & fluffy.
  4. Add oil & incorporate.
  5. Add egg whites & full incorporate.
  6. Add clear vanilla **regular vanilla will work just as well**
  7. Starting & ending with flour mixture, alternate between flour mixture & milk while being sure to whisk after each addition.
  8. Divide batter evenly between 5 bowls (there will be slightly under 1 cup of batter in each bowl).
  9. Use gel food coloring (red, orange, yellow, green, blue, purple) to color each bowl of batter to your desired vibrancy. Whisk in food coloring until evenly blended.
  10. Transfer each color of batter to its own piping bag and cut off the tips (careful not to spill the batter).
  11. Pipe about 1/4 cup of each color batter into each of the jars, layering the colors in this order: purple (first), blue, green, yellow, red (last).
  12. Place the jars in a glass baking dish. Add 1/4 inch of water to the bottom of the dish surrounding the jars. Bake for 35-40 minutes. Cake tops should spring back to the touch when done, but don't bake so long that the cakes are brown. You can also use a long cake skewer to test doneness if you have one.
  13. Allow cakes to cool completely (about one hour) in their water bath. DO NOT attempt to cool faster with cold water or placing in the fridge because this will stress the glass if your mason jars are not tempered properly.


  1. Sift 4 cups of powdered sugar & set bowl aside.
  2. Cream butter & shortening.
  3. Add vanilla.
  4. Scrape down the sides.
  5. Place your mixer on the lowest speed & slowly add in your powdered sugar, 1/2 cup at a time.
  6. Do not worry if your buttercream looks crumbly & dry because we will fix that next.
  7. Scrape down the sides one last time.
  8. With your mixer on a medium high speed, slowly add in heavy cream.
  9. Turn mixer up to a high speed and whip your buttercream until you have light & fluffy consistency you are looking for.
  10. Give each cake jar a heavy dollop of whipped cream and a generous splash of rainbow sprinkles.


  • Room Temperature Ingredients: Be sure to allow your dairy ingredients to reach room temperature. Room temperature ingredients not only combine more effortlessly (no accidental over-mixing) but they also trap air so much better. This trap air then expands and produces a fluffy, light texture during your baking process.
  • Prepared Pan: There will always be the “next best way to prepare your pans” before baking. Simply put however, the most effective way I find in my kitchen is a light rum of shortening around the sides, parchment paper on the bottom of the pan, and a very light dusting of flour (cocoa powder for chocolate baked goods) all throughout.

Be sure to subscribe & ring the bell on the MANCAKE baking channel for weekly recipes & tutorials this way you can bake right along with me. Click – MANCAKE YouTube Channel

More Recipes You Might Enjoy:

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More Cake Theme Tutorials👉’s have a Llama Party! I had so much fun working with fondant though more practice will definitely be needed😅 Also been enjoying learning new techniques to share with everyone here so keep sending those comments over on the MANCAKE channel with what you'd like to see make next. I'll see you all very soon with another yummy tutorial so be sure to ring the bell when you subscribe 👉

Posted by Man Cake on Wednesday, July 10, 2019

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