Rainbow Sprinkle Cake Recipe

Prep

Preheat oven to 350°F (175°C). Grease and flour two 8-inch round cake pans (or three 6-inch pans) using nonstick spray or softened butter and the tablespoon of flour; tap out excess. Line pan bottoms with parchment rounds for easy release.

Dry ingredients

In a medium bowl whisk together 2.5 cups all-purpose flour, 2 tsp baking powder, and 1/2 tsp fine salt until evenly combined. Set aside.

Cream butter and sugar

In the bowl of a stand mixer fitted with the paddle attachment (or using a large bowl and hand mixer), beat 3/4 cup softened unsalted butter and 1.75 cups granulated sugar on medium-high speed for 3–4 minutes, until pale and fluffy. Scrape down the bowl as needed.

Add eggs and extracts

With mixer on low, add the 4 large eggs one at a time, beating 20–30 seconds after each addition until incorporated. Add 2 tsp vanilla extract and 2 tbs vegetable oil; mix briefly to combine.

Alternate flour and milk

With mixer on low speed, add the dry ingredients in three additions alternately with 1 cup whole milk and 1/2 cup plain yogurt, beginning and ending with the dry ingredients (dry–milk–dry–milk–dry). Mix until just combined after each addition; do not overmix.

Add sprinkles

Place 3/4 cup rainbow sprinkles in a small bowl and toss with 1 tablespoon of flour to coat (this helps prevent sinking). Gently fold the coated sprinkles into the batter with a rubber spatula until evenly distributed.

Portion and color

Divide the batter evenly into 4 or 5 small bowls depending on how many colors you want (for a layered rainbow look you can do 4–5 colors). Add a small amount of gel food coloring to each bowl (about 1 tsp per color) and fold gently until fully colored. If you prefer a marbled/confetti look, you can leave the batter uncolored and just layer small dollops of colored batter into the pans.

Bake

Pour colored batters into the prepared pans — for two 8-inch layers, swirl or layer the colors in each pan to create a confetti/rainbow cross-section. Smooth the tops lightly. Bake in the preheated oven 22–28 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs and the cakes spring back when gently pressed. For three 6-inch pans, bake 15–20 minutes; adjust as needed.

Cool

Allow cakes to cool in pans on a wire rack for 10 minutes, then run a thin knife around the edges and invert onto racks to cool completely, about 1 hour. If layers dome significantly, level with a serrated knife when cool.

If using fresh strawberries, finely chop 1/2 cup and combine with 1 cup strawberry jam and 1 tsp lemon juice in a small bowl. Stir to combine. If jam is very thick, microwave for 10–15 seconds to loosen so it spreads easily. Taste and adjust for brightness with a bit more lemon if needed.

Beat butter

In a clean bowl, beat 1 cup softened unsalted butter on medium speed until smooth and creamy, about 1–2 minutes.

Add sugar and flavor

Gradually add 4 cups sifted confectioners' sugar, about 1 cup at a time, beating on low after each addition to avoid a sugar cloud. Once incorporated, add 2 tsp vanilla extract and 1/4 tsp fine salt.

Adjust texture

Increase mixer speed to medium and add 4 tablespoons heavy cream (or milk) one tablespoon at a time until you reach a spreadable, pipeable consistency. Beat 2–3 minutes more until light and fluffy. Taste and adjust salt or vanilla if desired.

Level and cut

If your cakes baked into domes, level them with a serrated knife so layers stack evenly. If you used one pan with all colors, carefully slice horizontally to create layers if desired.

Fill

Place the first cake layer on your serving plate or cake board. Spread an even layer (about 1/3 to 1/2 cup) of the strawberry jam mixture over the top, leaving a 1/4-inch border to prevent squeeze-out. If you like extra jam, add a bit more but keep it thin so the cake remains stable.

Crumb coat

Apply a thin layer of vanilla buttercream over the jam and the sides of the cake to seal in crumbs (about 1/2–3/4 cup buttercream). Chill the cake in the refrigerator 15–20 minutes to set the crumb coat.

Final frosting

Apply the remaining buttercream in a thicker, even layer over the top and sides of the cake. Use an offset spatula or bench scraper to smooth. If desired, tint a small portion of the buttercream with food coloring for piped decorations.

Add sprinkles

Press the remaining 1/2 cup rainbow sprinkles onto the sides and lightly on top of the cake. For a neater finish, gently roll the sides of the cake in a shallow pan of sprinkles while supporting the top with a spatula.

Chill and serve

Chill the finished cake 20–30 minutes to let the buttercream set. Remove from refrigerator 10–15 minutes before serving to soften slightly. Slice with a sharp knife wiped clean between cuts for tidy slices that reveal the rainbow confetti interior.