Big Batch Confetti Cake Buttercream

The first time I made confetti cake, my kitchen counter looked like a rainbow explosion. I had chosen the wrong sprinkles, those tiny nonpareils that bled streaks of gray through the batter instead of staying cheerful and bright. My daughter walked in, saw the mess, and declared it a masterpiece anyway.

Last summer I made three of these cakes in one weekend for graduation parties. By the third batch, I had stopped measuring the sprinkles exactly and just poured them in until the batter looked happy. Every single person asked for the recipe.

Ingredients

• All-purpose flour: Provides the structure that keeps this tall cake from collapsing under all those sprinkles
• Granulated sugar: Sweetens and tenderizes, creating that classic birthday cake crumb we all love
• Baking powder and baking soda: Work together to give the cake its impressive rise and fluffiness
• Fine sea salt: Balances sweetness and actually makes the vanilla flavor pop forward
• Whole milk: Room temperature milk incorporates better and creates a more tender crumb than cold
• Vegetable oil: Keeps the cake incredibly moist for days, unlike butter alone which can firm up
• Unsalted butter: Melted butter adds that rich flavor we crave while oil handles the moisture
• Large eggs: Room temperature eggs emulsify better into the batter for a uniform texture
• Pure vanilla extract: Do not skip this or use imitation, the difference is worth every penny
• Rainbow sprinkles: Use jimmies specifically, not nonpareils, or your colors will bleed into gray streaks
• Unsalted butter for frosting: Room temperature butter is non-negotiable for smooth, creamy buttercream
• Powdered sugar: Sift first to prevent lumps that will ruin that velvety frosting texture
• Whole milk for frosting: Adjust this to get exactly the consistency you want for spreading

Instructions

Preheat your oven and prepare the pans:

Heat to 350°F (175°C) and generously grease two 9x13-inch pans, then line with parchment so nothing sticks later.

Whisk together all the dry ingredients:

Combine flour, sugar, baking powder, baking soda, and salt in a large bowl, breaking up any clumps of sugar.

Mix the wet ingredients separately:

Whisk milk, oil, melted butter, eggs, and vanilla until completely smooth and uniform.

Combine wet and dry ingredients:

Pour the wet mixture into the dry and mix just until combined, some small lumps are fine.

Fold in the sprinkles gently:

Use a spatula to carefully fold in the sprinkles, taking care not to overmix the batter.

Divide and bake:

Split batter evenly between pans, smooth tops, and bake 30 to 35 minutes until a toothpick comes out clean.

Cool completely before frosting:

Let cakes rest in pans 10 minutes, then move to wire racks until fully cool to the touch.

Make the buttercream frosting:

Beat butter until creamy, about 2 minutes, then gradually add powdered sugar until incorporated.

Finish the frosting:

Add milk, vanilla, and salt, then beat on high for 3 minutes until light and fluffy.

Frost and decorate generously:

Spread thick frosting over each cooled cake and shower with sprinkles for that festive finish.

Save to Pinterest

This cake became my go-to the year my daughter turned seven. She helped pour the sprinkles and talked about how the cake would taste like happiness. It was the first birthday where I did not buy a store cake and nobody missed it.

Making Ahead

You can bake the cake layers a day ahead and wrap them tightly in plastic. The buttercream also keeps well in the refrigerator for two days, just let it come to room temperature and beat it again before frosting.

Storage

Leftovers stay surprisingly moist at room temperature for up to three days, covered with plastic or in an airtight container. The refrigeration actually makes the buttercream firm up too much for my taste.

Serving Suggestions

Cut squares smaller than you think you need because this cake is rich. A tall glass of cold milk is the perfect pairing, cutting through all that buttercream sweetness perfectly.

• Let the cake sit 15 minutes after frosting before serving so everything sets slightly
• Run your knife under hot water between cuts for perfect clean slices
• Save some sprinkles to replenish any spots that settle into the frosting

Save to Pinterest

There is something about a homemade confetti cake that feels like love in baking form. Hope it brings joy to your table.

Your Recipe Questions

→ What type of sprinkles work best in the cake batter?

Jimmies (the long, skinny sprinkles) perform best in cake batter. Nonpareils (the tiny round balls) tend to bleed color into the batter, creating gray streaks. Save nonpareils for decorating the top frosting only.

→ Can I make this as a layer cake instead of sheet cake?

Absolutely. Divide the batter between three 9-inch round pans instead of the rectangular baking pans. Reduce the baking time to 25-30 minutes, as the layers will bake faster than the larger sheet format.

→ Why use both butter and oil in the cake?

The combination creates the best of both worlds—butter provides rich flavor while oil ensures the cake stays moist and tender for days. This dual-fat approach produces an exceptionally soft crumb that doesn't dry out quickly.

→ How should I store the finished cake?

Keep the cake covered at room temperature for up to 3 days. For longer storage, refrigerate in an airtight container for up to a week. Bring to room temperature before serving for the best texture and flavor.

→ Can I freeze this confetti cake?

Yes, freeze unfrosted cake layers wrapped tightly in plastic and foil for up to 3 months. Thaw overnight at room temperature before frosting. You can also freeze frosted squares individually wrapped for grab-and-go treats.

→ What makes this frosting particularly creamy?

Beating room-temperature butter for a full 2 minutes before adding sugar creates an ultra-smooth base. Adding the powdered sugar gradually and finishing on high speed incorporates air, yielding a light, fluffy texture that spreads beautifully.