Six layers of colorful cake are tied together in a rainbow of deliciousness with icing. This recipe shows you how to ditch the box of cake mix and make a rainbow birthday cake from scratch. This recipe uses six different colors of soft food gel paste to get the bright, vibrant colors. You can order them all in a single kit on Amazon.
* Multiply serving weight in grams by the carbs-per-gram ratio to calculate the total estimated carbs.
Two Hours Before Starting
8 large eggs, room temperature
1 cup whole milk, room temperature
Two hours before you plan on making the cake, remove eggs and milk from fridge and let come to room temperature.
1 pound (4 sticks) butter
Place butter on a plate and let rise to room temperature to soften.
Cake Pan and Oven Prep
vegetable shortening
flour
parchment or wax paper
Adjust oven rack to lower-middle position and heat oven to 350°F. Generously grease six 9 inch cake pans with vegetable shortening and cover pan bottoms with rounds of parchment paper or wax paper. Grease parchment rounds, dust cake pans with flour, and tap out excess. (If you do not have six cake pans, prepare as many pans as you do have and repeat this step later on to cook remaining batter.)
In a small bowl, whisk together eggs, milk, and vanilla. Set aside.
596g / 3 cups sugar
400g / 3 ½ cups cake flour
4 teaspoons baking powder
2 teaspoons salt
In a large bowl, whisk together sugar, cake flour, baking powder, and salt.
reserved butter
Add butter and use a pastry blender to cut the butter into small, pea-sized pieces with the flour.
1 ½ cups of reversed egg-milk-vanilla mixture
Add 1 ½ cups of reserved egg-milk-vanilla mixture and mix at lowest speed with a hand mixer until incorporated, 5 to 10 seconds.
remaining egg-milk-vanilla-mixture
Increase speed to high, add remaining egg mixture, and beat until light and fluffy, about 1 minute.
Stop mixer and thoroughly scrape sides and bottom of bowl. Beat on medium-high until thoroughly combined and batter looks slightly curdled, about 15 seconds longer.
Pour equal amounts of batter (about 1 cup) into six separate bowls.
Add purple food coloring to the first bowl and mix to combine. Note: Use a clean spatula to mix each bowl of batter to avoid spreading colors into different bowls.
Add red food coloring to the sixth bowl and mix with a clean spatula.
Baking
Pour each bowl of batter into a separate prepared cake pan. Spread batter to sides of pan and smooth with rubber spatula. (Note: If you do not have six cake pans, then bake as many as you are able to, clean your pan(s), prepare them again as noted above, and cook remaining layers.)
Bake until edges of cake turn golden and a toothpick inserted in center comes out clean, about 18 minutes. Cakes may rise in center slightly but will level when cooled.
Remove pan from oven and cool on rack for 10 minutes. Run a knife around the perimeter of the pan to loosen. Invert cake onto large plate, peel off parchment, and reinvert onto lightly greased rack. Cool completely before icing.
Decorating
884g / 30 ounces white frosting
Place the purple layer on the bottom of a plate or cake platter. Cover generously with white frosting. Repeat with remaining layers in rainbow sequence of blue, green, yellow, orange, red.
Two hours before you plan on making the cake, remove eggs and milk from fridge and let come to room temperature.
Place butter on a plate and let rise to room temperature to soften.
Adjust oven rack to lower-middle position and heat oven to 350°F. Generously grease six 9 inch cake pans with vegetable shortening and cover pan bottoms with rounds of parchment paper or wax paper. Grease parchment rounds, dust cake pans with flour, and tap out excess. (If you do not have six cake pans, prepare as many pans as you do have and repeat this step later on to cook remaining batter.)
In a small bowl, whisk together eggs, milk, and vanilla. Set aside.
In a large bowl, whisk together sugar, cake flour, baking powder, and salt.
Add butter and use a pastry blender to cut the butter into small, pea-sized pieces with the flour.
Add 1 ½ cups of reserved egg-milk-vanilla mixture and mix at lowest speed with a hand mixer until incorporated, 5 to 10 seconds.
Increase speed to high, add remaining egg mixture, and beat until light and fluffy, about 1 minute.
Stop mixer and thoroughly scrape sides and bottom of bowl. Beat on medium-high until thoroughly combined and batter looks slightly curdled, about 15 seconds longer.
Pour equal amounts of batter (about 1 cup) into six separate bowls.
Add purple food coloring to the first bowl and mix to combine. Note: Use a clean spatula to mix each bowl of batter to avoid spreading colors into different bowls.
Add blue food coloring to the second bowl and mix with a clean spatula.
Add green food coloring to the third bowl and mix with a clean spatula.
Add yellow food coloring to the fourth bowl and mix with a clean spatula.
Add orange food coloring to the fifth bowl and mix with a clean spatula.
Add red food coloring to the sixth bowl and mix with a clean spatula.
Pour each bowl of batter into a separate prepared cake pan. Spread batter to sides of pan and smooth with rubber spatula. (Note: If you do not have six cake pans, then bake as many as you are able to, clean your pan(s), prepare them again as noted above, and cook remaining layers.)
Bake until edges of cake turn golden and a toothpick inserted in center comes out clean, about 18 minutes. Cakes may rise in center slightly but will level when cooled.
Remove pan from oven and cool on rack for 10 minutes. Run a knife around the perimeter of the pan to loosen. Invert cake onto large plate, peel off parchment, and reinvert onto lightly greased rack. Cool completely before icing.
Place the purple layer on the bottom of a plate or cake platter. Cover generously with white frosting. Repeat with remaining layers in rainbow sequence of blue, green, yellow, orange, red.
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