Color is something that instantly makes us smile and keeps our senses intrigued. But what happens when a simple shade is traded in for, say, an entire rainbow? When you decide to paint a kaleidoscope on a freshly-made cake, you can feel your smile burst into joy and your taste buds perk up at the mere thought of creamy frosting and bright sprinkles. Whether you have an upcoming unicorn-themed birthday party to throw, or you just want to learn how to make a beautiful cake, then grab your pans and food dye — you're about to make a delightfully vibrant, ombre dessert.
Make the Cakes
Preheat the oven to 350 degrees Fahrenheit. In the bowl of a stand mixer, with the paddle attachment fitted, pour in the cake mix, water, vegetable oil, eggs and yogurt. Mix on medium-high speed for two minutes. Then, grease the cake pans with vegetable oil, and pour the batter in each pan, divided evenly. Bake for 25 to 28 minutes. The cakes are done when you can place a toothpick in the middle and it comes out clean. Remove from oven and let them cool.
To get firmer cakes that are easier to cut and frost, cover them in plastic wrap and place in the freezer for at least 20 minutes after baking.
Make the Frosting and Crumb Coat
While the cakes are cooling in the freezer, prepare the frosting. Mix the softened cream cheese and milk in a stand mixer with the whisk attachment. Whisk for about two minutes on medium-high speed until the cheese is smooth and creamy, and there are no lumps. Add in the softened butter and vanilla, and whip the cream base on high until it's light and fluffy, or for about two minutes.
Slowly add in the powdered sugar, one cup at a time, until the frosting is thick and smooth. Cover and set aside. Remove the cakes from the freezer and cut the tops so they are smooth and flat. Place one cake on the stand, and spread a 1/2-inch layer of frosting on top. Then place the second cake on top, and spread on a layer of frosting to crumb-coat the entire cake.
Mix Frosting Colors and Pipe on the Cake
There should be about 1 to 2 cups of frosting leftover after crumb-coating the cake with a base layer. Divide the frosting evenly into six small bowls. Create the colors of the rainbow (red, orange, yellow, green, blue, violet) with the gel food dye. Use separate spoons and about a pea size of gel to mix each color. Using the spoons for each corresponding color, place a one-inch thick stripe of each color on top of the cake.
Smooth and Blend the Frosting
Using the flat edge of the icing smoother, start at the top of the cake and pull down vertically in the direction of the colors. Clean off the edge and repeat this motion until the entire top is smooth. There should be some excess frosting down on the sides of the cake. Still using the flat edge of the smoother, blend the colors around the edges of the cake, spinning it as you make a swirled tie-dye frosting pattern on the sides. Do this until the cake is entirely smooth and blended. Be careful not to over-blend, though, as it will begin to turn a muddy color if you do.
Add Sprinkles and Serve
Top the cake with a thick layer of rainbow sprinkles and it's ready to eat. The cake can be served immediately or stored in the refrigerator or freezer for up to four days. Enjoy!