Funfetti Birthday Cake with Rainbow Buttercream and Sprinkles

The first time I made this funfetti birthday cake with rainbow buttercream and sprinkles was for a neighborhood kid’s party and the moment I walked in with it everyone gasped and smiled from ear to ear. It was like carrying a slice of happiness topped with color and joy and even the adults couldn’t resist taking pictures before diving into a slice.

From that celebration on and because it’s packed with cheerful sprinkles and soft vanilla cake and it’s covered in bright buttery frosting and fun textures this cake has become my favorite way to mark special moments with extra flair. It’s the kind of cake that brings out the child in everyone and adds a festive touch no matter the occasion.

Ingredients

• Here’s what I use for this recipe. You can always make substitutions if you prefer!
• All-purpose flour – Builds the base of the cake while keeping it fluffy and soft.
• Baking powder – Helps the cake rise evenly and keeps it light.
• Salt – Balances the sweetness and enhances the vanilla flavor.
• Unsalted butter – Adds rich flavor and creates a tender crumb.
• Granulated sugar – Sweetens the cake and helps with structure.
• Eggs – Bind the ingredients and add richness.
• Vanilla extract – Brings out the nostalgic bakery-style flavor.
• Whole milk – Adds moisture and helps the batter come together.
• Sour cream – Keeps the cake ultra moist and adds a slight tang.
• Rainbow sprinkles – Mixed into the batter for that signature funfetti look.
• Powdered sugar – Sweetens and stabilizes the buttercream.
• Heavy cream – Lightens the frosting and makes it silky.
• Food coloring – Used to tint the frosting into bright rainbow layers.

Tools You’ll Need

• Mixing bowls – To mix the batter and separate the buttercream colors.
• Hand or stand mixer – Essential for creaming butter and beating frosting to the right texture.
• Cake pans – I use three 8-inch round pans to build height.
• Rubber spatula – For folding in sprinkles and scraping the sides of the bowl.
• Offset spatula – Helps spread and smooth each colored buttercream layer.
• Piping bags – Great for swirling the top with pink frosting.
• Gel food coloring – Gives vibrant color without thinning out the frosting.
• Cake turntable (optional) – Makes decorating with layers smoother and more fun.

Instructions

Step 1: Preheat the Oven

I preheat the oven to 350°F and grease three 8-inch cake pans then line the bottoms with parchment paper for a clean release.

Step 2: Mix the Dry Ingredients

In a bowl I whisk together flour, baking powder, and salt then set it aside while I prepare the wet ingredients.

Step 3: Cream the Butter and Sugar

Using my mixer I beat the butter and sugar until pale and fluffy which takes about 3–5 minutes then I add the eggs one at a time.

Step 4: Add Vanilla, Milk, and Sour Cream

I stir in the vanilla extract then alternate adding the milk and sour cream with the dry ingredients until the batter is smooth and thick.

Step 5: Fold in the Sprinkles

I gently fold in the rainbow sprinkles making sure not to overmix so they don’t bleed too much into the batter.

Step 6: Bake the Cakes

I divide the batter evenly into the pans and bake for 25–30 minutes or until the tops spring back when lightly touched then I cool them completely.

Step 7: Make the Buttercream

I beat butter until creamy then gradually add powdered sugar and a splash of heavy cream and once smooth I divide the frosting into bowls and color each with food gel.

Step 8: Assemble the Cake

I start stacking the cake layers with plain buttercream in between and then I apply the rainbow-colored buttercream in horizontal sections around the cake.

Step 9: Smooth and Swirl

Using an offset spatula I gently smooth the buttercream around the sides for a blended look then I pipe pink swirls on top.

Step 10: Add the Sprinkles

I press rainbow sprinkles around the base and scatter more across the top to finish the cake with a colorful celebration vibe.

Tips

If you want your sprinkles to stay bright in the batter use jimmies instead of nonpareils because they don’t bleed as easily. I also chill the cake briefly after frosting to help everything set before slicing. And for extra fun you can fill the center with surprise sprinkles that spill out when you cut it!

Ways to Serve

At a child’s birthday party or colorful celebration

With rainbow-themed decorations or party favors

Alongside vanilla or cotton candy ice cream

Topped with candles and edible glitter for extra sparkle

As a cupcake version using the same batter and frosting colors

Frequently Asked Questions

Can I use store-bought cake mix for the funfetti birthday cake with rainbow buttercream and sprinkles?

Yes and while homemade gives more flavor, boxed mix with added sour cream and sprinkles can work in a pinch.

How do I store the funfetti birthday cake with rainbow buttercream and sprinkles?

I cover it and refrigerate it then bring it to room temperature before serving to soften the buttercream.

Can I freeze funfetti birthday cake with rainbow buttercream and sprinkles?

Yes and I freeze the unfrosted layers wrapped tightly and thaw before decorating.

See You in the Kitchen

I hope you try this funfetti birthday cake with rainbow buttercream and sprinkles because it’s pure joy in every slice and it brings the magic of celebration to any day. Let me know how you decorate yours and don’t forget to share the fun!

Happy Cooking!

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