This funfetti sheet cake is tender, airy, and studded with colorful sprinkles, finished with a silky vanilla buttercream. It’s an easy homemade celebration cake that serves a crowd—ideal for birthdays, parties, and any cheerful occasion.
Some desserts instantly lift the mood, and this funfetti sheet cake does just that. The crumb is soft and tender thanks to cake flour and buttermilk, while a combination of butter and oil keeps it flavorful and moist for days. Bright rainbow jimmies are folded into the batter so each slice is full of festive color, and a cloud-like vanilla buttercream completes the classic celebration look.
Made entirely from scratch, this cake gives you the nostalgic fun of boxed mixes with a superior texture and real vanilla flavor. It’s straightforward to prepare and easy to decorate—perfect when you need a large, portable dessert that disappears fast.
Why You’ll Love This Funfetti Sheet Cake
- From scratch: all the classic funfetti charm without a boxed mix.
- Soft, tender crumb: cake flour, buttermilk, butter, and oil produce a light yet sliceable texture.
- Celebration-ready: ideal for birthdays, showers, graduations, potlucks, and more.
- Simple to decorate: a spread of buttercream and plenty of sprinkles is all you need.
- Feeds a crowd: the 9×13-inch pan yields many servings and is easy to transport.
- Make-ahead friendly: bake a day ahead to simplify decorating the next day.
Key Ingredients
- Cake flour – provides a soft, fine crumb while keeping slices sturdy enough to frost and serve. For a tender bakery-style cake, cake flour is recommended.
- Buttermilk – adds moisture and a slight tang that balances sweetness and helps create a light texture.
- Butter and oil – butter gives rich flavor; oil keeps the cake tender and moist over time.
- Vanilla extract – good vanilla is essential in a simple vanilla cake; it brightens the flavor and pairs perfectly with sprinkles and buttercream.
- Rainbow jimmies – choose jimmies (long sprinkles) to avoid color bleeding in the batter and to preserve bright spots of color.
- Vanilla buttercream – a classic, airy buttercream is the ideal finishing touch: creamy, easy to spread, and pipeable for borders or rosettes.
How to Make Funfetti Sheet Cake
Mix the batter.
Whisk the dry ingredients together first. In a separate bowl, cream the softened butter and granulated sugar until light and fluffy, then add the oil, eggs (one at a time), and vanilla. With the mixer on low, add the dry ingredients in three additions, alternating with two additions of buttermilk. Mix just until combined after each addition—over-mixing can toughen the cake.
Fold in the sprinkles.
Gently fold the rainbow jimmies into the batter with a spatula. Use jimmies rather than nonpareils to avoid color streaking and to keep the sprinkles from dissolving into the batter.
Bake.
Spread the batter evenly in the prepared 9×13-inch pan and bake until the top springs back lightly and a toothpick inserted near the center comes out with a few moist crumbs. Allow the cake to cool completely before frosting so the buttercream remains light rather than melting.
Make the buttercream.
Beat softened butter until smooth, then slowly add sifted confectioners’ sugar on low speed. Add vanilla, a pinch of salt, and 2 tablespoons of heavy cream or milk, then increase the mixer speed and beat until the frosting is light and fluffy. Add more cream a little at a time if needed to reach the desired spreadable consistency.
Frost and decorate.
Spread the buttercream over the cooled cake with an offset spatula. Pipe a simple border if desired and finish with a generous scattering of sprinkles for a classic funfetti look.
Tips for Success
- Use room-temperature ingredients. Butter, eggs, and buttermilk blend together more smoothly and produce a uniform batter and even crumb.
- Measure flour properly. Too much flour makes cakes dense. For best results, weigh the flour or spoon and level it when using measuring cups.
- Mix just until combined. Over-mixing develops gluten and can make the cake heavy.
- Choose jimmies over nonpareils. Jimmies keep their shape and color better while baking; nonpareils often bleed color.
- Cool completely before frosting. Even a slightly warm cake can make buttercream soft and difficult to work with.
- Chill for cleaner slices. For neat slices, refrigerate the frosted cake for 20–30 minutes before cutting.
Variations and Serving Ideas
- Change the sprinkles: swap in seasonal or themed colors to match holidays, showers, graduations, or team events.
- Dress it up: add sanding sugar, piped rosettes, candy pearls, or candles for extra flair.
- Serve with ice cream: a slice is delightful with vanilla or a birthday-cake flavored ice cream.
- Want individual portions? make confetti cupcakes using the same batter and frosting for portable treats.
How to Store
Room temperature: Keep the cake covered in an airtight container at cool room temperature for up to 2 days. If your kitchen is warm, refrigerate instead.
Refrigerator: Store covered or in an airtight container for up to 5 days. Bring to room temperature before serving for best flavor and texture.
Make ahead: You may bake the cake a day ahead. Once cool, wrap or cover tightly and frost the next day.
Buttercream can be made up to 2 days in advance; refrigerate in an airtight container and re-whip after it returns to room temperature to restore lightness.
Freezer: Freeze an unfrosted cake, well wrapped, for up to 3 months. Thaw overnight in the refrigerator before frosting. Individually wrap frosted slices and freeze up to 2 months; thaw in the refrigerator or at room temperature for an hour.
Bring More Fun to the Dessert Table
Whether you’re marking a milestone or simply want to bake a cheerful dessert, this funfetti sheet cake is sure to please. The soft vanilla crumb, colorful sprinkles, and cloud-like buttercream create a homemade classic that’s as fun to make as it is to share. Try customizing the sprinkles or frosting decoration to suit your event and enjoy the smiles that follow.
If you make the cake, consider noting any adjustments you made to timing or decoration so you can reproduce your perfect version next time.
Funfetti Sheet Cake
Ingredients
For the cake:
- 2 ½ cups (300 g) cake flour
- 2 teaspoons baking powder
- ½ teaspoon baking soda
- ¾ teaspoon salt
- ¾ cup (170 g) unsalted butter, softened
- 1 ½ cups (300 g) granulated sugar
- ¼ cup (60 ml) neutral oil (vegetable or canola)
- 4 large eggs, at room temperature
- 2 tablespoons vanilla extract
- 1 cup (240 ml) buttermilk, at room temperature
- ½ cup (80–90 g) rainbow jimmie sprinkles, plus more for decorating
For the frosting:
- 1 ½ cups (339 g) unsalted butter, softened
- 5 cups (550 g) confectioners’ sugar, sifted
- 2 teaspoons vanilla extract
- Pinch to ¼ teaspoon salt, to taste
- 2–4 tablespoons (30–60 ml) heavy cream or milk
Instructions
To make the cake:
- Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking pan and line with parchment if desired.
- Whisk together the cake flour, baking powder, baking soda, and salt; set aside.
- In a large bowl, beat the softened butter and sugar on medium speed until light and fluffy.
- Add the oil and mix until incorporated.
- Add the eggs one at a time, mixing well after each, then mix in the vanilla.
- With the mixer on low, add the flour mixture in three additions, alternating with two additions of buttermilk. Mix just until combined.
- Gently fold in the sprinkles using a spatula.
- Spread the batter evenly in the prepared pan. Bake 32–38 minutes, or until the top springs back lightly and a toothpick inserted near the center comes out with a few moist crumbs.
- Cool completely in the pan on a wire rack before frosting.
To make the frosting:
- Beat the softened butter on medium speed until smooth and creamy.
- With the mixer on low, gradually add the sifted confectioners’ sugar until incorporated.
- Add the vanilla, salt, and 2 tablespoons (30 ml) cream or milk. Add more cream, a little at a time, until the frosting is fluffy and spreadable.
- Increase the mixer speed to medium-high and beat 2–3 minutes until lightened and airy.
- Frost the cooled cake, pipe a border if desired, and sprinkle additional jimmies on top.
Notes
- Use rainbow jimmies (long sprinkles) to prevent color bleeding during baking.
- Accurate measuring of cake flour helps ensure the softest crumb—use a scale or spoon-and-level when measuring.
- Mix just until the batter comes together to keep the cake light and tender.
- Allow the cake to cool fully before frosting to avoid softening the buttercream.
- For tidy slices, chill the frosted cake 20–30 minutes before cutting.
- Makes about 15–24 servings depending on slice size; the recipe is scaled for 20 servings.