How to Bake a Confetti Birthday Cake
Bake and decorate a classic scratch-made confetti layer cake with vibrant, bleed-free rainbow sprinkles and fluffy vanilla buttercream frosting.
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🧰 Required Tools & Equipment
- ✓ Two 8-inch round cake pans
- ✓ Electric hand mixer or stand mixer
- ✓ Parchment paper
- ✓ Silicone spatula
- ✓ Offset spatula
- ✓ Wire cooling rack
- ✓ Toothpick or cake tester
📦 Materials & Supplies
- ✓ 2 1/2 cups all-purpose flour
- ✓ 2 1/2 tsp baking powder & 1/2 tsp salt
- ✓ 1 cup unsalted butter, softened
- ✓ 1 1/2 cups granulated sugar
- ✓ 3 large eggs + 1 egg white (room temperature)
- ✓ 1 cup whole milk or buttermilk
- ✓ 1/2 cup rainbow jimmies sprinkles
- ✓ 4 cups powdered sugar
⚠️ Safety Checkpoints & Warnings
- • Always use thick, dry oven mitts when handling preheated pans and removing hot cake layers from the oven.
- • Switch off and unplug electric mixer beaters before scraping the bowl with a spatula.
- • Ensure raw flour and raw egg batter are not tasted or consumed prior to thorough baking.
📋 Step-by-Step Guide (6 Steps)
Prep Pans and Whisk Dry Ingredients
Preheat oven to 350°F (175°C). Grease two 8-inch cake pans with butter or cooking spray, line the bottoms with parchment paper rounds, and grease the paper. In a medium bowl, whisk together flour, baking powder, and salt until uniformly blended.
- • Cake pans show a glossy greased interior with flat, circular parchment fitted flush to the bottom.
- • Dry ingredients are aerated with no visible lumps of baking powder.
- • Skipping parchment paper circles, causing cake bottoms to stick and tear upon release.
Cream Butter and Sugar, Then Add Eggs
In a large bowl, beat softened butter and granulated sugar on medium-high speed for 3 to 4 minutes until pale, light, and fluffy. Add eggs and egg white one at a time, beating for 30 seconds after each addition, then mix in 1 tablespoon of vanilla extract.
- • Butter-sugar mixture has expanded in volume and turned a pale ivory color.
- • Batter is smooth, emulsified, and holds soft crests without curds.
- • Using cold, hard butter, leading to dense pockets and poor air incorporation.
- • Dumping all eggs in at once, causing the emulsion to break.
Alternate Liquids and Fold in Sprinkles
Add dry ingredients in three additions alternating with the milk in two additions, mixing on low speed just until combined. Gently fold in the rainbow jimmies with a silicone spatula using wide scooping motions until evenly distributed, stopping immediately to prevent color bleeding.
- • Thick, smooth cake batter with brightly colored sprinkles intact and evenly dispersed throughout.
- • No unmixed streaks of dry flour or pool of milk along bowl walls.
- • Using tiny round nonpareil sprinkles, which dissolve instantly and turn batter gray/muddy.
- • Overmixing with the electric mixer after adding sprinkles.
Divide Batter and Bake
Divide batter evenly between the two prepared pans and level the tops with a spatula. Bake at 350°F (175°C) for 25 to 30 minutes until golden, the centers spring back when lightly touched, and a toothpick inserted into the center comes out clean or with a few moist crumbs.
- • Cakes are golden blonde on top, slightly pulling away from the pan edges.
- • Toothpick withdrawn from the center shows no wet batter.
- • Opening the oven door repeatedly in the first 20 minutes, causing cake centers to collapse.
Cool Cakes and Whip Buttercream Frosting
Cool cakes in pans on a wire rack for 15 minutes, then invert onto racks to cool completely. Meanwhile, beat 1 cup softened butter until creamy, gradually add 4 cups powdered sugar, 3 tablespoons heavy cream, and 1 tsp vanilla, beating on medium-high for 3 minutes until light and spreading consistency.
- • Cake rounds are cold to the touch and resting on wire racks with parchment peeled off.
- • Buttercream holds silky, spreadable peaks without sliding off the spatula.
- • Frosting warm cakes, which instantly melts the butter and makes the frosting slide off.
Layer, Crumb Coat, and Decorate
Place first cake layer on a plate, spread 3/4 cup frosting over top, and crown with the second layer. Coat the entire cake with a thin crumb coat layer of frosting, chill 15 minutes to set, then apply the final thick frosting layer and press handfuls of rainbow sprinkles around the sides and top.
- • Level two-layer cake fully enclosed in opaque, smooth white frosting.
- • Bright rainbow sprinkles cleanly adhered across the top perimeter or base border.
- • Skipping the thin crumb coat, resulting in cake crumbs showing through the outer white frosting.
Don’t have everything?
- No Buttermilk? 1 cup whole milk stirred with 1 tablespoon white vinegar or lemon juice (rest for 5 minutes)
- No Offset spatula? The smooth back of a large butter knife or metal dinner spoon
- No Parchment paper? Heavy layer of butter dusted thoroughly with flour, tapping out excess