Rainbow cake is the ultimate celebration cake—bright, fun, and surprisingly easy. With soft, moist layers baked in vibrant colors and stacked with creamy buttercream, it turns any birthday or party into a happy moment. Let’s make yours shine.
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This rainbow cake is a colorful layer cake with soft vanilla sponge and creamy buttercream. With six vibrant layers, it’s the perfect cake for birthdays, kids’ parties, or any celebration.
Each layer is a fluffy white cake tinted in bright colors, filled with a light mascarpone whipped cream, then covered in smooth buttercream and finished with a colorful drip. A homemade rainbow cake that’s as delicious as it is stunning.
Why you'll love this recipe
Ingredients You Need
- Cake layers: cake flour, granulated sugar, baking powder, baking soda, egg whites, buttermilk, unsalted butter, vanilla extract, gel food coloring.
- Filling: heavy cream, mascarpone cheese, powdered sugar, vanilla.
- Buttercream frosting: unsalted butter, powdered sugar, heavy cream, vanilla extract.
- Drip: white chocolate, heavy cream, gel food coloring.
Want to see my tools? Here’s what I use for all my cakes.
How To Make Rainbow Cake
Here are a few quick step-by-step visuals. Don’t forget that the full instructions with exact ingredient amounts are in the recipe card below!
In a large mixing bowl, whisk together the unsalted butter and granulated sugar until the cake batter is light and creamy.
Add the egg whites gradually along with the vanilla extract, whisking well after each addition to keep the mixture fluffy. This is the key to a soft and moist sponge for your rainbow layer cake.
Finish by gently folding in the sifted flour and buttermilk, alternating between the two. Use a spatula and mix until the cake batter is smooth and well combined, perfect for baking even layers for your rainbow cake.
Divide the cake batter evenly into six portions using a kitchen scale and transfer them into small mixing bowls. Add gel food coloring to each portion and stir until you reach the desired shade.
Pour the colored batter into six 6-inch cake pans, lined on the bottom with parchment paper only. Bake in a preheated oven at 325°F (160°C) for 18 to 20 minutes, or until the rainbow cake layers are set in the center.
Place the purple sponge first on a cake board set on a turntable. Spread a layer of mascarpone whipped cream on top, then cover with the blue sponge.
Repeat with the green, yellow, and orange layers, finishing with the red sponge on top to complete your rainbow cake.
Cover the entire layer cake with buttercream frosting and smooth it out using a cake scraper. Chill the cake in the fridge until the buttercream is firm to the touch.
Next, pour the colorful drip around the edges, then finish by piping swirls on top and adding rainbow sprinkles for decoration.
Tips for this recipe
Variations & Substitutions
Recipe Questions
Can I make a rainbow cake without food coloring? → Yes, but the colors will be more muted. Natural food powders (like beet, matcha, turmeric) can work, but the classic vibrant rainbow comes from gel food coloring.
How do I keep the cake layers moist? → Don’t overbake the sponges and make sure to chill the cake before frosting. Using mascarpone whipped cream and buttercream also helps lock in moisture.
Can I make the cake ahead of time? → Yes! You can bake the layers 1–2 days in advance and assemble the cake the day you serve it.
What frosting works best for a rainbow cake? → A light mascarpone whipped cream paired with buttercream for smoothing works perfectly, but you can also use Swiss buttercream or cream cheese frosting.
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I hope you enjoyed this rainbow cake recipe! Don’t forget to leave a rating and a comment below to let me know what you think. Happy baking!
Rainbow Cake
- Total Time: 1 hour
- Yield: 8 - 10 slices
Description
A colorful rainbow layer cake with six fluffy sponges, filled with light mascarpone whipped cream, covered in buttercream frosting, and decorated with a colorful drip. (For a 6-inch cake – about 8 to 10 servings)
Ingredients
White Cake Layers
- 3 ¼ cups (415 g) cake flour
- 2 ½ tsp (11 g) baking powder
- ¾ tsp (4 g) baking soda
- ½ tsp salt
- 1 cup (225 g) unsalted butter, softened
- 1 ¾ cups (370 g) granulated sugar
- 6 large egg whites (about 210 g)
- 1 ⅓ cups (330 ml) buttermilk
- 3 tsp vanilla extract
- Gel food coloring: red, orange, yellow, green, blue, purple
Mascarpone Whipped Cream Filling
- 7 oz (200 g) mascarpone cheese, chilled
- 1 ¼ cups (300 g) heavy cream, cold
- 3 tbsp powdered sugar
- 1 tsp vanilla extract
Buttercream Frosting
Follow my American Buttercream Frosting recipe
Rainbow Drip
- 4 ¼ oz (120 g) white chocolate, finely chopped
- 3 tbsp (45 ml) heavy cream
- Gel or oil-based food coloring: red, orange, yellow, green, blue, purple
Instructions
For the Cake Layers
- Preheat the oven to 325°F (160°C), convection/fan. Grease and line the bottoms of six 6-inch (15 cm) round cake pans with parchment paper.
- In a large mixing bowl (or the bowl of a stand mixer), beat the softened butter and granulated sugar until light and creamy.
- Add the egg whites gradually along with the vanilla extract, mixing well after each addition until the batter is fluffy.
- Using a spatula, gently fold in the sifted flour, baking powder, baking soda, and salt, alternating with the buttermilk, until the cake batter is smooth and well combined.
- Divide the batter evenly into six bowls using a kitchen scale.
- Tint each portion with gel food coloring (red, orange, yellow, green, blue, violet) and stir until the color is fully incorporated.
- Pour the colored batters into the prepared cake pans and bake for 18–20 minutes, or until a toothpick inserted in the center comes out clean.
- Let the cakes cool in the pans for 5 minutes, then remove and transfer to a wire rack to cool completely.
For the Buttercream Frosting
Prepare the buttercream following my American Buttercream recipe and set aside.
For the Mascarpone Whipped Cream
- In a chilled mixing bowl, whip the cold heavy cream, cold mascarpone, powdered sugar, and vanilla extract together until stiff peaks form.
- Keep refrigerated until ready to assemble.
To Assemble the Layer Cake
- Place the purple sponge layer on a cake board set on a turntable.
- Spread an even layer of mascarpone whipped cream with an offset spatula, then top with the blue sponge.
- Repeat with the green, yellow, and orange layers, finishing with the red layer on top. (Chill for 20 minutes if needed to stabilize.)
- Cover the cake with a thin crumb coat of buttercream frosting, smooth, and refrigerate for 30 minutes.
- Add a second, thicker layer of buttercream, smooth with a cake scraper, and chill until firm to the touch.
For the Drip and Decoration
- Melt the white chocolate and heavy cream together in the microwave or over a double boiler until smooth and fluid.
- Divide into six small bowls, tint with gel food coloring, and let cool to about 86°F (30°C) before using.
- Drip the colorful ganache around the edges of the chilled cake.
- Finish by piping buttercream swirls on top and sprinkling with rainbow sprinkles.
- Serve the rainbow layer cake, or refrigerate and bring to room temperature for at least 30 minutes before slicing.
Notes
Storage: This rainbow cake keeps well for up to 2 days in the refrigerator, covered with a cake dome or stored in an airtight container. Bring it out at least 30 minutes before serving so the cream softens back to the right texture.
Tips:
- The cup measurements are approximate. For best results in baking, always use a kitchen scale instead of relying only on cups.
- Use gel food coloring (brands like Wilton, Americolor, or Rainbow Dust) for vibrant colors that stay bright after baking.
- Weigh each portion of batter to get even, consistent cake layers.
- Level the sponges with a cake leveler or a large serrated knife for a clean assembly.
- Assemble inside a tall acetate cake collar (or a deep cake ring) to keep the layers stable.
- Chill the cake between steps of frosting and decorating—this makes smoothing and adding the drip much easier.
- Prep Time: 40 minutes
- Cook Time: 20 minutes
- Category: cake, layer cake
- Cuisine: American
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