Sheet Pan Confetti Birthday Cake with Vanilla Buttercream

By AislePrompt Editorial · Published 2026-05-01 · Updated 2026-05-01

A festive vanilla sheet cake loaded with colorful sprinkles and topped with a smooth homemade buttercream frosting. This American-inspired recipe, ready in about 60 minutes, layers all-purpose flour, baking powder, salt into a dessert worth slowing down for — great for weekend baking, holiday tables, or any time you want a sweet payoff at the end of a meal. Each serving lands at about 450 calories and feeds 12, so it slots into a weekend bake or a special-occasion dessert tray. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Ingredients

• 2 1/2 cups all-purpose flour
• 2 1/2 tsp baking powder
• 1/2 tsp salt
• 1 cup unsalted butter, softened
• 2 cups granulated sugar
• 4 large eggs
• 2 tsp vanilla extract
• 1 cup whole milk
• 1/2 cup rainbow sprinkles
• 1 cup unsalted butter for frosting, softened
• 4 cups powdered sugar
• 2 tbsp heavy cream
• 1 tsp vanilla extract for frosting

Stand mixers worth buying for baking like this → Best Stand Mixers for 2026: Top Picks + Buying Guide

Instructions

1. Step 1: Preheat the oven to 350°F and grease a 9x13 inch sheet pan with butter and lightly dust with flour.
2. Step 2: In a medium bowl, whisk together 2 1/2 cups all-purpose flour, 2 1/2 teaspoons baking powder, and 1/2 teaspoon salt; set aside.
3. Step 3: In a large bowl, use a hand mixer to cream 1 cup softened unsalted butter and 2 cups granulated sugar until light and fluffy, about 3-4 minutes. Beat in 4 large eggs one at a time, then mix in 2 teaspoons vanilla extract.
4. Step 4: Alternate adding the flour mixture and 1 cup whole milk to the butter mixture in three additions, beginning and ending with the flour, mixing just until combined.
5. Step 5: Fold in 1/2 cup rainbow sprinkles gently to avoid melting the colors.
6. Step 6: Pour the batter into the prepared sheet pan and smooth the top. Bake for 35-40 minutes until a toothpick inserted near the center comes out clean.
7. Step 7: For the frosting, beat 1 cup softened unsalted butter with 4 cups powdered sugar, 2 tablespoons heavy cream, and 1 teaspoon vanilla extract until fluffy and spreadable.
8. Step 8: Let the cake cool completely before spreading the buttercream evenly over the top, then garnish with extra sprinkles if desired.