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–+ servings
A half Rainbow cake on a golden paper plate.
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5 from 8 votes

Rainbow Cake step-by-step tutorial

This easy Rainbow cake recipe is one of the beautiful cakes with colorful layers and a super easy, light cream cheese frosting! Not only the most colorful cakes of all but also tastes really amazing with vanilla and cream cheese notes. A super delicious and fun cake to make from scratch, you will love it!
Prep Time1 hour
Cook Time1 hour
Waiting time4 hours
Total Time6 hours
Course: Dessert
Cuisine: American
Servings: 8
Calories: 1081kcal
Author: Katalin Nagy

Equipment

Ingredients

For the 6 cake layers

Frosting + Decoration

Metric - US Customary

Instructions

For the rainbow layers

  • Decide how many cake layers you want to bake at once depending on how many baking pans you own, I recommend 3 pans at least so you can bake this cake in 2 batches. The steps below assume 6 pans (all 6 colours) made at the same time. If you have 2 pans, make only ⅓ of the recipe using 2 colours then repeat the same process for another 2 colours then one last time with the last 2 colours. If you have 3 pans, make ½ of the recipe then repeat. The recipe quantity can be easily divided into either 3 or 2.
  • Heat the oven to 170 C / 338°F (no fan) and prepare your baking pans
  • Start with preparing 6 small bowls and divide milk into 6 with the help of your Digital scale
  • Mix gel food coloring into milk one by one, there will be 6 colors: red, yellow, orange, blue, purple, and green. Use a toothpick and start with a small amount until bright color achieved
  • Cream room temperature butter and sugar together in a stand mixer until pale and fluffy then beat the eggs in, one at a time
  • Sift flour, salt, and baking powder together, this is the “dry ingredients”
  • Fold dry ingredients with the butter-sugar mixture until combined
  • Divide now the mixture into 6 equal portions using a digital scale
  • Mix each portion with one of the colored milk so at the end you will have 6 equal portions of cake batter. If you are unhappy with the color of your batter at this point, mix in some more coloring
  • Pour the cake batter into 6 different baking pans
  • Bake them for 20 min or until a skewer inserted comes out clean. Let them cool on a cooling rack before frosting

Frosting

  • For the frosting beat mascarpone, cream cheese, vanilla bean paste and powder sugar until smooth and fluffy, this will only take few minutes. Use an hand mixer and do not over beat as it can become runny

Assemble and Decoration

  • Start building up the cake from the bottom (purple) to the top (red) and spread the frosting in between the layers equally. I suggest 100g per layer, use a digital scale to measure
  • If at any point the frosting gets soft or the cake gets unstable, place it into the fridge to chill then only after continue
  • Once all the layers are assembled, place the cake into the fridge for 1h to set then on a turntable apply your first crumb coat around the cake
  • Let the cake rest again for 1h in the fridge before applying your final coating
  • Divide the remaining frosting into 6 equal quantities and color them. Decorate the top and side of the cake according to your liking
  • Store cake in the fridge however let it come to room temp for 30-60min before serving for the softest, most moist texture

Notes

Ingredient notes:
  1. Measure your ingredients with a Digital scale for accuracy
  2. While preparing the sponges, make sure all ingredients are at room temperature
  3. Good quality butter and pure vanilla are the heart of making this cake. Use high-quality 82% fat content European butter and the best quality vanilla for the frosting
  4. To achieve bright color on your sponge, you will have to use high-quality gel or powder food coloring eg. Wilton
Baking technique notes:
  1. Make sure you read my Expert tips section above to maximize your success. A short recipe alone is not able to cover all the necessary details, and science behind baking.
  2. While baking the sponge layer, remember not to overbake it. Over-baked sponge cake can become too dry
  3. Cream cheese frosting is very easy to overwhip. When whipping the frosting stop as soon as the mixture reached a fluffy consistency (will take 1-2 minutes). It won´t get stiffer after this point, in fact, if you overbeat it, it will get only runner, then it will break
  4. Chill the sponges before assembling
  5. During assembling, if at any point the frosting feels soft, the cake feels unstable during assembling, place it into the fridge for 1h to chill then continue with the next layer

Nutrition

Calories: 1081kcal | Carbohydrates: 69g | Protein: 14g | Fat: 85g | Saturated Fat: 49g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 18g | Trans Fat: 1g | Cholesterol: 290mg | Sodium: 732mg | Potassium: 243mg | Fiber: 1g | Sugar: 52g | Vitamin A: 2916IU | Calcium: 279mg | Iron: 2mg