Single-Layer Funfetti Cake Recipe for Bright, Moist Celebration Cakes

Add a little fun to your next dessert with this 6-inch Single Layer Funfetti Cake. Tender and moist, the cake is studded with rainbow jimmies and pairs beautifully with a small-batch vanilla flour (Ermine) buttercream. Top it with extra sprinkles for a festive finish—this easy single-layer cake serves about six and is perfect for small celebrations or a special treat.

Table of Contents

• 8 Reasons to Love This Recipe
• Ingredients Needed
• Substitutions
• Homemade Cake Flour Substitute
• What is Flour Buttercream?
• How to Make Small-Batch Vanilla Flour Buttercream
• Make Your Own Sprinkle Mix
• FAQs
• Essential Cake Making Tools
• More Small-Batch Dessert Recipes
• Single Layer Funfetti Cake Recipe

8 Reasons to Love This Recipe

1. Simple to make with everyday ingredients.
2. Yields a single 6-inch cake that’s tall enough to slice into two layers.
3. Serves about 6 people.
4. Moist and tender texture thanks to buttermilk.
5. Rainbow jimmies add a cheerful look and fun texture.
6. Paired with a vanilla flour buttercream (no powdered sugar) for a less-sweet frosting.
7. Ideal for small gatherings, birthdays, or a cozy treat for yourself.
8. Make a custom sprinkle mix for decorating.

Ingredients Needed

To make this moist vanilla funfetti cake and the small-batch flour buttercream, you’ll need:

• Cake flour
• Baking powder
• Salt
• Unsalted butter (room temperature)
• Granulated sugar
• 1 large egg (room temperature)
• Vanilla extract
• Buttermilk
• Rainbow jimmies (or sprinkles) plus extra for decoration
• For the flour buttercream: all-purpose flour, milk, granulated sugar, salt, and additional unsalted butter

Substitutions

Cake flour substitute: If you don’t have cake flour, use the homemade substitute below.

Buttermilk: If you don’t have buttermilk, use whole milk with 2 teaspoons lemon juice (add lemon juice to the measuring cup, then fill to 1/3 cup with milk and let sit 5 minutes to thicken).

This recipe has not been tested with alternative flours, egg substitutes, or dairy-free swaps.

Homemade Cake Flour Substitute

Make a quick cake flour substitute with all-purpose flour and cornstarch:

1. Add 1 tablespoon cornstarch to a 1/2-cup measure.
2. Fill the rest of the 1/2-cup with all-purpose flour.
3. Sift the mixture once or twice for a finer texture.

Double the batch to store extra in an airtight container at room temperature or in the freezer.

What is Flour Buttercream?

Flour buttercream, also called Ermine or boiled milk buttercream, is made without powdered sugar. It uses cooked flour and milk as the base and is finished by beating in butter and vanilla. The result is a silky, less-sweet frosting with a texture similar to Swiss meringue but with the richness of American buttercream.

How to Make Small-Batch Vanilla Flour Buttercream

This buttercream is made in two parts: a cooked flour mixture and beaten butter. Allow time for cooling so both components reach room temperature.

Step 1: Whisk the all-purpose flour, granulated sugar, and salt together, then add the milk and whisk again.

Step 2: Heat the mixture over low–medium heat, stirring constantly and scraping the pan bottom, until it thickens to a paste with a glossy appearance.

Step 3: After it bubbles, remove from heat and stir 1–2 minutes more to release heat and reduce glossiness.

Step 4: Spread the mixture on a plate and press plastic wrap directly onto the surface to prevent a skin. Cool fully to room temperature (you can speed this in the refrigerator, then bring back to room temperature before using).

Step 5: Beat room-temperature butter until light and fluffy (2–3 minutes). Add the cooled flour mixture one spoonful at a time on low speed, letting each addition incorporate before adding more.

Step 6: Scrape the bowl, add vanilla, and beat on medium-high until smooth. If the frosting is thin, it usually means the cooked mixture or butter wasn’t at room temperature. If it’s grainy, ensure both components are fully at room temperature before combining.

You can make the cooked flour mixture or the assembled buttercream 3–5 days ahead; refrigerate and bring to room temperature before re-whipping to refresh the texture.

Make Your Own Sprinkle Mix

Create a homemade sprinkle blend for decorating by combining a few types of sprinkles. A balanced mix might include:

• Rainbow jimmies or classic rainbow sprinkles
• Rainbow nonpareils
• Rainbow confetti sprinkles

Use muted or naturally colored sprinkles if you prefer a softer look. Combine small amounts in a jar with a tight lid and shake to blend.

FAQs