10-Minute Rainbow Cake Layer Stack
Stack store-bought sponge cakes with vibrant food-colored frosting for an Instagram-worthy rainbow layer cake in under 5 minutes. No baking required—just assembly and a chill.
- Total time
- 10 min
- Servings
- 8
- Calories
- 380
- Protein
- 2g
Ingredients
- 1 package store-bought vanilla sponge cake layers (3–4 thin, about 6 inches wide)
- ½ cup unsalted butter, softened
- 2 cups powdered sugar
- 6 drops per color food coloring (red, orange, yellow, green, blue, purple)
- 2 tbsp milk
- ¼ cup sprinkles (rainbow or pearl)
Instructions
- 1
Divide softened butter among six small bowls, about 1.5 tbsp each.
- 2
Add one-sixth of the powdered sugar to each bowl, then 1 tsp milk.
- 3
Add 6 drops of a different food color to each bowl—red, orange, yellow, green, blue, purple.
- 4
Whisk each frosting until smooth and spreadable, about 60 seconds per color.
- 5
Place one cake layer on a serving plate, spread with red frosting, then top with the next layer.
- 6
Repeat with remaining layers and colors (orange, yellow, green, blue, purple), stacking as you go.
- 7
Frost the outside of the stacked cake with any leftover frosting, then press sprinkles all over.
- 8
Chill for at least 5 minutes before slicing to let layers set and frosting firm up.
Tools you’ll need
- six small bowls
- whisk
- offset spatula or butter knife
- serving plate
- sharp serrated knife
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