Add a little fun to your next dessert with this 6-inch Single Layer Funfetti Cake. This small-batch cake is moist and tender, studded with rainbow jimmies. For extra vanilla flavor, pair it with the small-batch vanilla flour buttercream and finish with a sprinkle mix of your choice. It’s an easy, delicious single-layer cake that’s perfect for small gatherings 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
- Simple to make for bakers of any level.
- Produces a single 6-inch cake that’s thick enough to slice into two layers.
- Serves about 6 people—ideal for small celebrations.
- Moist and tender crumb thanks to buttermilk.
- Sprinkles (rainbow jimmies) add a cheerful, nostalgic touch.
- Paired with a vanilla flour buttercream (no powdered sugar required).
- Great for intimate birthdays, dinner parties, or treating yourself.
- You can create a custom sprinkle mix for decoration.
Ingredients Needed
For the cake and the small-batch vanilla flour buttercream, you will need:
- Cake flour
- Baking powder
- Salt
- Unsalted butter
- Granulated sugar
- 1 large egg
- Vanilla extract
- Buttermilk
- Rainbow jimmies (sprinkles) plus extra for decoration
- All-purpose flour and milk for the flour buttercream
Substitutions
Cake flour substitute: If you don’t have cake flour, you can make a substitute (see the Homemade Cake Flour Substitute section below).
Buttermilk alternative: If you don’t have buttermilk, use whole milk with 2 teaspoons lemon juice stirred in. Let it sit about 5 minutes to thicken.
This recipe wasn’t tested with gluten-free or dairy-free swaps, egg replacements, or alternative pans—results may vary.
Homemade Cake Flour Substitute
If you don’t have cake flour, make a light substitute with all-purpose flour and cornstarch. You will also need a sifter.
To make one 1/2 cup of cake flour:
- Add 1 tablespoon cornstarch to a 1/2 cup measuring cup.
- Fill the rest of the cup with all-purpose flour.
- Sift the mixture once or twice for a finer texture.
Double the quantities to store extra, and keep in an airtight container at room temperature or in the freezer.
What Is Flour Buttercream?
Flour buttercream, also called Ermine buttercream or boiled milk frosting, is a less-sweet frosting made without powdered sugar. It combines all-purpose flour, granulated sugar, salt, milk, vanilla extract, and unsalted butter. The result is a creamy, smooth buttercream with a texture similar to Swiss meringue but with the richness of classic American buttercream.
How to Make Small-Batch Vanilla Flour Buttercream
The flour buttercream is prepared in two parts: a cooked flour paste and whipped butter. Both components must be at room temperature before combining.
STEP ONE: Whisk the all-purpose flour, granulated sugar, and salt in a small saucepan. Add the milk and whisk until smooth.
STEP TWO: Over low-medium heat, stir constantly until the mixture reaches a near boil. Scrape the bottom while stirring. The paste will thicken and become glossy.
STEP THREE: When bubbling, remove from heat and stir for 1–2 more minutes to release heat and reduce gloss.
STEP FOUR: Spread the mixture on a plate, press plastic wrap directly onto the surface to prevent a skin, and cool to room temperature. To speed cooling, refrigerate briefly, then return to room temperature before continuing.
STEP FIVE: Beat room-temperature unsalted butter (cut into cubes) on medium-high for 2–3 minutes until light and fluffy.
STEP SIX: With the mixer on low, add the cooled flour mixture one spoonful at a time, allowing each addition to incorporate before adding more. Scrape the bowl, add vanilla, and whip on medium-high until smooth and fluffy. If stored, refrigerate and bring to room temperature before rewhipping for 2–3 minutes.
Tip: Cooling the thickened flour mixture in the refrigerator shortens wait time. Make sure both the mixture and the butter are fully at room temperature before combining.
Make Your Own Sprinkle Mix
To create a simple homemade sprinkle mix for decorating, combine:
- Rainbow jimmies (or rainbow sprinkles)
- Rainbow nonpareils
- Rainbow confetti sprinkles
Choose natural or muted colors if you prefer a softer look. Combine equal amounts in a jar with a tight lid and shake to blend. Store in a cool, dry place.
FAQs
Because this batter yields a thicker cake, a 6″ x 3″ pan is recommended. A 6″ x 2″ pan will likely fill to the top.
A serrated knife is ideal for cleanly slicing the cake into layers.
This small-batch buttercream yields about 1 1/4 cups—enough to cover the cake and provide a thin filling if you split the cake.
If the cooked flour mixture or the butter was too warm or too soft when combined, the frosting can become thin. Ensure both components are truly at room temperature before mixing.
If the cooked flour mixture is still cool when mixed with butter, or if either component is not at room temperature, the frosting can become grainy. Bring both to room temperature and rewhip.
A mix of rainbow jimmies, rainbow nonpareils, and rainbow confetti sprinkles was used for the decoration.
Essential Cake-Making Tools
More Small-Batch Dessert Recipes
Small Batch Vanilla Cupcakes
Small Batch Cinnamon Rolls
Single Layer Carrot Cake
Small Lemon Cream Cheese Pound Cake
Single Layer Funfetti Cake
Ingredients
Single Layer Funfetti Cake
- 1 cup Cake flour
- 1 tsp Baking powder
- 1/4 tsp Salt
- 5 tbsp Unsalted butter, room temperature
- 1/2 cup Granulated sugar
- 1 Large egg, room temperature
- 1 tsp Vanilla extract
- 1/3 cup Buttermilk
- 1/4 cup Rainbow jimmies (or rainbow sprinkles)
Small-Batch Vanilla Flour Buttercream Frosting
- 3 tbsp All-purpose flour
- 1/2 cup Granulated sugar
- 1/4 tsp Salt
- 1/2 cup Milk
- 1/2 cup Unsalted butter, room temperature and cut into pieces
- 1 tsp Vanilla extract
Homemade Funfetti Mix (for decoration)
- 1/4 cup Rainbow jimmies
- 1/4 cup Rainbow nonpareils
- 1/4 cup Rainbow confetti
Instructions
Single Layer Funfetti Cake
- Preheat the oven to 350ºF and position the rack just above center. Generously spray a 6-inch round cake pan (6″ x 3″ recommended) with a flour-based baking spray. Line the bottom with parchment and lightly respray.
- Sift together the cake flour, baking powder, and salt in a medium bowl and set aside.
- Using a mixer with the paddle attachment or a hand mixer, beat the unsalted butter and granulated sugar on medium-high until light and fluffy.
- Add the egg and vanilla extract and mix until combined.
- With the mixer on low, add the dry ingredients in thirds alternating with the buttermilk, mixing until just combined. Fold in the rainbow jimmies.
- Transfer the batter to the prepared pan and bake 35–40 minutes or until a toothpick inserted in the center comes out clean or with a few dry crumbs.
- Cool the cake in the pan for 10 minutes, then invert onto a wire rack to cool completely before frosting.
Small-Batch Vanilla Flour Buttercream Frosting
- Combine the all-purpose flour, granulated sugar, and salt in a small saucepan. Whisk in the milk until smooth.
- Over low-medium heat, stir constantly until the mixture thickens to a paste and becomes glossy. Scrape the bottom while stirring to prevent scorching.
- When the mixture bubbles, remove from heat and stir for 1–2 minutes. Spread the mixture onto a plate and press plastic wrap directly onto the surface to prevent a skin. Cool to room temperature.
- Beat the room-temperature unsalted butter on medium-high for 2–3 minutes until light and fluffy. With the mixer on low, add the cooled flour mixture one spoonful at a time until fully incorporated.
- Scrape the bowl, add vanilla, and mix on medium until smooth and fluffy. If needed, rewhip after storing to restore texture.
Homemade Funfetti Mix
- Combine rainbow jimmies, nonpareils, and confetti in a jar with a lid. Close and shake to blend. Use to decorate the frosted cake.
Assembling the Cake
- If desired, slice the cooled cake into two layers with a serrated knife. Place the first layer on a serving plate, spread a thin layer of frosting, then top with the second layer.
- Frost the outside of the cake, then press the homemade funfetti mix onto the frosting for a festive finish. Serve and enjoy.
Notes
- Recipe times listed do not include the time needed to make the frosting.
- A 6″ x 3″ pan is recommended for best results; a 6″ x 2″ pan may be very full.
- To cool the cooked flour mixture faster, chill briefly in the refrigerator, then bring it back to room temperature before combining with butter.
- Flour buttercream tips inspired by techniques shared by other bakers—ensure both components are at room temperature for a smooth result.
Nutrition
Nutritional information is an estimate and will vary based on specific ingredients used.
If you try this single-layer funfetti cake, please leave a comment and rating—feedback helps other bakers and is greatly appreciated.