Princess Heart Cake with Rainbow and Homemade Confetti Cake

Recently I was asked to make a heart cake for a 3-year-old little princess whose party consisted of “so many people I wouldn’t know how to count.” I was asked to make the bottom tier a very large square and the top two tiers large hearts. I was also asked to make the cake look like these decorations:

Okay, so one 16x16x3 square with (1) 12×3 heart and (1) 8×3 heart coming up, I said with a smile, while inwardly dying a bit inside. The amount of batter it would take to even fill up the bottom tier had my mind trying to process mathematical calculations I hadn’t contemplated since my SAT days.

Princess’ Mom: “Oh, and I’d like the bottom and top tier to be rainbow, with the middle confetti. Think you could do that?”

Me: “Sure, of course!” [Screams inside with sheer panic]. Now not only would I need about 5 gallons of batter, it had to be divvied up evenly into the colors of the rainbow. And confetti cake from scratch? Did that even exist? [It does, and I’ll provide the recipe below]

“Meris,” said my friend, Shana, her super logical mind asking a question my artistic, happy-go-lucky mind was too flighty to process, “Is a pan that size even going to fit in your tiny oven?”

Oh, well…crap.

Turns out it did, barely, but the fridge? That was a whole other issue. Let’s just say that over the course of 2 days many cake layers played fridge musical chairs.

But hey, all little princesses deserve beautiful cakes. So with a little research, courageous balls of steel, ordering really weird things like glucose from Amazon, and one severely overworked stand mixer, it all came together over the course of a week.

And truth be told, making the cakes of my childhood dreams was a lot of fun, especially since Christina Tosi of Momofuku’s Milk Bar has the perfect recipe for confetti cake and white, creamy frosting.

Happy birthday, little lady. I hope your birthday cookout was all the pink, rainbow, confetti blowout your 3-year-old mind couldn’t possibly handle 😉

Homemade Confetti Birthday Cake

[Makes enough batter for 1 quarter sheet pan cake. For a 12×3 I multiplied this recipe by 3]


  • Stand mixer
  • Parchment paper


  • 1/2 stick [4 Tbl.] salted butter at rm. temp.
  • 1/3 cup vegetable shortening
  • 1 1/4 cups granulated sugar
  • 3 Tbl. tightly packed light brown sugar
  • 3 eggs
  • 1/2 cup buttermilk
  • 1/3 cup grapeseed oil [do not sub this oil for veggie oil. It’s the grapeseed flavor that makes the cake taste like confetti-trust me on this]
  • 2 tsp. clear vanilla extract [same rule applies for clear vanilla as the grapeseed oil]
  • 2 cups cake flour
  • 1 1/2 tsp. baking powder
  • 3/4 tsp. kosher salt
  • 1/4 cup rainbow sprinkles + 2 Tbl. rainbow sprinkles

Heat oven to 350 degrees. Grease and flour your baking pan [I use Wilton’s cake release] and line the bottom with parchment paper.

Combine the butter, shortening, and both sugars in bowl of stand mixer fitted with the paddle attachment and cream together on medium-high for 2-3 min. Scrape down sides of the bowl, add the eggs, and mix on medium-high for 2-3 min. Scrape down sides of the bowl again.

On low speed, stream in the buttermilk, oil, and vanilla. Increase the mixer speed to medium-high and paddle for 4-6 min, until the mixture is practically white, twice the size of your original butter and sugar mix, and completely homogenous. *Note: Don’t rush the process. You’re forcing too much liquid into an already fatty mixture that doesn’t want to make room for the liquid. There should be no streaks of fat or liquid. Stop the mixture and scrape down the sides of the bowl.

On very low speed, add the cake flour, baking powder, salt, and the 1/4 cup rainbow sprinkles. Mix for 45-60 seconds, just until your batter comes together. Scrape down sides of the bowl again.

Using a spatula, spread the cake batter into the pan in an even layer. Sprinkle the remaining 2 Tbl. sprinkles over the top of the batter.

Bake for 30-35 min. The cake will rise and puff, doubling in size, but will remain buttery and dense. At 30 min, gently poke the edge of the cake with your finger: the cake should bounce back slightly and the center should no longer be jiggly. Leave the cake in the oven for another 3-5 min. if it doesn’t pass these tests.

Take cake out of oven and cool on a wire rack. Cake keeps, stored in the fridge, covered in frosting or wrapped in plastic wrap 5 days.

Rainbow Cake

Rainbow cake is made taking a basic white cake mix and then coloring it with the six colors of the rainbow: purple, blue, green, yellow, orange, and red.

Here’s the recipe for a basic white cake [makes (2) 8”, (1) 9” or 24 cupcakes. I multiplied this recipe by 6 for the 16x16x3]:


  • Stand or electric mixer
  • Parchment paper


  • 3 cups sifted flour
  • 1 Tbl. baking powder
  • 1/2 tsp. salt
  • 2 sticks unsalted butter, rm temp
  • 2 cups sugar
  • 4 eggs, separated
  • 1 cup whole milk
  • 1 tsp. vanilla extract

Preheat oven to 350. Grease and flour your pan and line bottom with parchment paper. Sift together the flour, baking powder, and salt in a large bowl and set aside.

In a stand mixer, beat butter until soft and smooth. Add sugar and beat until light and smooth. Add egg yolks, one at a time, beating after each addition and scraping down sides. On low, alternate adding flour and milk, beginning and ending with the flour. Stir in vanilla extract.

In another bowl, with clean beaters, beat the egg whites until stiff but not dry. Stir in a 1/2 cup of whites into the batter, then fold in the rest in several additions.

Now, most people make rainbow cakes by making thin sheet cakes out of each of the 6 colors, but since I couldn’t do that with the tiers, I divided the batter evenly into 6 bowls, coloring each a separate color.

After making the 6 colors, I would spread one of the bottom [purple] then covered that layer with the next [blue] and so on until red was the final color. The good news is, the batter is thick enough that you can spread the batter in layers without worrying that they’re going to run together.

Divide batter between pans and smooth. Bake 30-35 min.

Birthday Cake/ Homemade Store-Bought White Frosting

[Makes about 2 cups of frosting]


  • Stand mixer


  • 1 stick [8 Tbl.] salted butter, rm. temp.
  • 1/4 cup vegetable shortening
  • 2 oz. cream cheese
  • 1 Tbl. glucose
  • 1 Tbl. corn syrup
  • 1 Tbl. clear vanilla extract
  • 1 1/4 cups confectioner’s sugar, sifted
  • 1/4 tsp. kosher salt
  • Pinch of baking powder
  • Pinch of citric acid [I tried this and thought it tasted horrible so I cut this out of my recipe]

Combine the butter, shortening, and cream cheese in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium-high speed for 2-3 min., until the mix is smooth and fluffy. Scrape down sides of bowl.

With the mixer on its lowest speed, stream in the glucose, corn syrup, and vanilla. Crank mixer up to medium-high and beat 2-3 min., until the mix is silky smooth and a glossy white. Scrape down sides of bowl.

Add the confectioner’s sugar, salt, baking powder, and citric acid [optional!] and mix on low speed just to incorporate. Crank speed back to medium-high and beat for 2-3 min., until you have a brilliant white, super smooth frosting. Use immediately or store in an airtight container in the fridge for up to one week.

Side view


Front and side designs

Up close. These were made using stencils and royal icing tinted black

The cake topper is pretty common online and can be found here


4 thoughts on “Princess Heart Cake with Rainbow and Homemade Confetti Cake

  1. Pingback: Twitter Cupcakes | Baking Things

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