Rainbow Alphabet Birthday Cake

This is not a cake blog. I am not a cake baker, though I have learned a few things over the years. I make cakes for special occasions and specifically for my kids birthdays. I grew up with a mom who always made special homemade cake for our birthday. By special I mean, “cut-out” animals, Barbie dolls coming out of cake and lots of theming. This was our favorite part of our birthday; dreaming up what our cake would be and then the big surprise when it was revealed that day. I have carried on this tradition with my own kids. I enjoy thinking up a fun cake for them, usually with their input, and then surprising them on their special day. 

My little four-year-old has been dreaming up the cake he’s wanted for his birthday for months. All of these dreams don’t seem to have a common theme “A bird cake! A “house” cake! A “chair” cake!” Basically anything he sees can be turned into a cake in his mind. Knowing this I realized that I could make any cake I wanted and he would be a happy camper. I have always been intrigued with the rainbow cakes I’ve seen online and decided that this was the year to give it a go. My little guy also loves learning his letters and sounds right now, so I figured that we could combine those two things into a perfect four-year-old birthday cake.

This cake definitely takes some time. It is not a quick recipe. You will have a lot of dishes at the end. The awe and surprise of rainbow colors in the cake is worth the extra time and effort. A few tips before you get started: use GEL food coloring (affiliate link). The liquid food coloring does not give the bright, bright colors you are looking for in this cake.

This cake is delicious with and without food coloring. It is a really good homemade white cake. You could modify it a bit if you don’t want to add the food coloring and just want a yummy white cake…but you won’t get that “shock and awe” factor when you cut into it. You could also use a box mix for the cake recipe if you don’t want to try your hand at homemade. I’m guessing you would need 2-3 box mixes of white cake, about 1 1/2 cups of batter per layer in a 9 inch pan.

Another tip: the icing on this cake is sweet. My kids love it that way. If I was making this for an all-adult party I may choose a Swiss Buttercream that isn’t quite so sweet (you will still need about 6 cups worth). If you love sweet icing, this is the cake for you (or your kids). My little guy was in awe when he came down the stairs, ran to the table and just stared at this awesome birthday cake. He loved it and that made the whole process worth it. I hope you will love it too.

If you want to watch a short 3 minute video of how I made this cake, click here.

Yield: 1 large, 6 layer-rainbow cake with about 6 cups of icing

Time: 30 minute mix, 17-20 minute bake, 1 ½ hours make icing/decorate/assemble



  • 12 oz (1 ½ cups) unsalted butter, room temperature
  • 21 oz (about 3 cups) white sugar
  • 9 large egg whites, room temperature
  • 21 oz (a scant 5 cups) all purpose flour 
  • 3 teaspoons baking powder
  • 1 teaspoon salt
  • 15 oz (1 ¾ cups plus 2 Tablespoons) milk, room temperature
  • 3 oz (⅓ cup plus 2 Tablespoons) vegetable oil
  • 1 teaspoon almond extract, optional
  • 1 teaspoon vanilla extract
  • Gel food coloring: red, orange, yellow, green, blue, purple


  • 3 cups unsalted butter, room temperature
  • 12 cups powdered sugar
  • 6 Tablespoons heavy cream 
  • 3 teaspoons vanilla extract
  • 1 teaspoon almond extract optional


  1. In a stand mixer using a paddle attachment, mix the butter until creamy and smooth. Add the sugar and whip on high until light and white in color (about 5 minutes).
  2. Crack the eggs and keep the egg whites together in a measuring cup. If your eggs are cold, you can briefly warm the egg whites in the microwave for a few seconds. Be careful doing this so you don’t end up with scrambled egg whites! Cold egg whites will mess up this batter, so make sure they are room temperature before using.
  3. In a separate bowl combine the flour, baking powder and salt. Set aside.
  4. In a large measuring cup combine the milk, vegetable oil and extracts and set aside.
  5. To the butter mixture and with the mixer running, add the egg whites a little at a time and let them fully incorporate before adding the next.
  6. Add in ⅓ of the dry ingredients and combine. Then add in ½ of the milk mixture. Combine. Add another ⅓ of the dry ingredients, then the rest of the milk mixture and then the last of the dry ingredients. Mix until just combined.
  7. Preheat the oven to 335 degrees. 
  8. Get out six small bowls and scoop about 13.5 ounces (about 1 ½ cups) of batter into each bowl.  
  9. Add a different gel color to each bowl of batter and mix it up.
  10. Prepare 9 inch cake pans. Trace the bottom of the pan on parchment paper and cut out the parchment paper to fit in the bottom of the cake pan. Repeat for the remaining 5 layers. Grease the sides of the pan with butter and flour to prevent sticking. If you only have two pans you can bake the cakes two at a time. It will take a little more time, but it is doable. You can also use an 8 inch cake pan but will need to add a few more minutes to the bake time.
  11. Pour the batter into the cake pan and bake the cakes for 17-20 minutes until a toothpick comes out clean. If you’ve used a smaller-sized pan, let the cake bake a little bit longer.
  12. Let the cakes cool about 10 minutes before turning them out on a cooling rack. Once cakes are cooled they can be wrapped in foil and frozen until you are ready to frost the cake.


  1. Using the whipping attachment on a stand mixer, whip the butter until it is creamy. Turn the mixer off and add 6 cups of the powdered sugar and heavy cream. Carefully turn the mixer back on (low speed) so the powdered sugar doesn’t fly up in your face. Whip together. Add the vanilla and almond (if using) extracts and whip some more. Gradually add in the rest of the powdered sugar a cup at a time and continue whipping until light, white, fluffy and everything is incorporated. The key to this buttercream is to whip it for longer than you think you should–at least 5-7 minutes. If the icing seems too thick, add a little more cream, a Tablespoon at a time.
  2. Take your cakes out of the freezer. Using a cake turntable (affiliate link) put a little bit of icing on the bottom of the turntable. Layer your cakes in the order of the rainbow with purple on the bottom, then blue, green, yellow, orange and red. In between each layer of cake add about ½ cup of icing and spread to the edges. Add about 1 ½ cups of icing on the top of the red layer of cake and slowly bring the icing down the sides of the cake using an offset spatula. Continue icing around the sides of the cake and smoothing them down. It is okay if you can see the layers through the icing right now. You actually want to see them a little bit. This is called the crumb coat. Once the entire cake is covered in icing and you have smoothed the sides down, put it in the fridge for the icing to harden for about 20-30 minutes.
  3. Pull your cake back out to work with. Using another 1 ½ cups of icing, cover the entire cake again, making sure to fill in any gaps where color could be seen. Smooth the icing using a bench scraper or other tool as you spin the cake around. Transfer the cake to the plate/cake board it will be served on. Decorate the cake as you wish. I decorated my cake with ABCs, and a simple dot border around the edges.
  4. Place the cake back in the fridge and pull out a few hours before serving to come to room temperature. I like to ice my cakes the night before I am serving them. If you have any fondant decorations, put them on after taking your cake out of the fridge so they don’t wilt. Enjoy!

Recipe Notes: I bought red fondant at the grocery store and formed the letters to my son’s name using small cake pop/caramel apple sticks. If you are planning to do this, create any fondant decorations a few days ahead of time so they will thoroughly dry out. Pop those decorations on the cake last-minute because you don’t want them sitting in the fridge, receiving moisture and making them bendable again.

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One Comment

  1. This is an unforgettable cake! I LOVED surprising you guys with your birthday cake each year… always the best part of your birthday! So glad JUDE had a fabulous cake and celebration this year!! Love it!! 🌈🎂🎉❤️