A homemade Funfetti Cake is a colorful celebration dessert filled with rainbow sprinkles and rich vanilla flavor. This version has three soft, moist cake layers covered with creamy vanilla buttercream and finished with even more sprinkles. The combination of butter, vegetable or canola oil, sour cream, buttermilk, and whole eggs creates a tender cake with enough richness to make every slice feel special. It is particularly well suited to birthdays, parties, anniversaries, and other celebrations.

Unlike an ordinary vanilla cake decorated with sprinkles only on the outside, a true funfetti-style cake has colorful sprinkles folded directly into the batter. When the layers are sliced, the rainbow colors appear throughout the crumb. This recipe uses ¾ cup of rainbow jimmies inside the cake and another ½ cup of sprinkles for decorating the finished buttercream. The result is a classic homemade birthday cake appearance without relying on a boxed cake mix.

What Does Funfetti Cake Taste Like?

Funfetti cake is based around a sweet vanilla flavor, but its texture is richer than many basic vanilla cakes. Butter contributes flavor, while vegetable or canola oil helps maintain moisture. Whole eggs add richness and structure, and full-fat sour cream provides another source of moisture. Buttermilk completes the batter and works alongside the other ingredients to create a tender homemade cake.

Vanilla is particularly important because there are few competing flavors in the recipe. One tablespoon of vanilla extract goes into the cake batter, while another tablespoon flavors the buttercream. This gives both the cake and frosting a noticeable vanilla character. The rainbow sprinkles contribute the familiar funfetti appearance, making the finished dessert colorful without changing the fundamental vanilla flavor of the cake.

Why This Homemade Funfetti Cake Stays Moist

The recipe uses both butter and oil instead of depending on only one type of fat. Butter contributes the rich flavor expected from homemade cake, while oil helps create and maintain a moist crumb. The addition of full-fat sour cream and buttermilk supplies further moisture, which is especially useful in a three-layer cake that needs enough structure for stacking without becoming dry or overly firm.

Correct baking time is equally important. Three 9-inch layers require approximately 30 to 35 minutes at 350°F, while 8-inch layers need approximately 35 to 40 minutes. The cakes are ready when a toothpick inserted into the center comes out clean. Removing them at the appropriate point helps preserve their soft texture instead of allowing excess baking time to dry out the crumb.

Start With Room-Temperature Ingredients

Room-temperature ingredients are important for achieving an evenly mixed cake batter. The butter, eggs, sour cream, and buttermilk should all be brought to room temperature before mixing. Ingredients at similar temperatures combine more smoothly, helping the butter, eggs, liquids, and fats form a more consistent batter. This contributes to more predictable baking and a better finished texture.

Cold ingredients can make softened butter firm up again or prevent the mixture from emulsifying properly. For a recipe containing several dairy ingredients and fats, giving everything enough time to reach room temperature is therefore worth the small amount of planning involved. The buttercream also calls for room-temperature butter and milk, helping create a smooth frosting that can be spread easily over the cooled cake.

Cream the Butter and Sugar Properly

The first major mixing step is creaming one cup of unsalted butter with two cups of granulated sugar. Using a hand mixer or stand mixer fitted with a paddle attachment, beat them together on medium-high speed for approximately three minutes. The mixture should become noticeably lighter and fluffier before the remaining ingredients are introduced.

This step incorporates air into the mixture and establishes an important part of the cake’s structure. Because the recipe also contains whole eggs and oil, properly creaming the butter and sugar helps prevent the finished cake from feeling unnecessarily heavy. Avoid rushing this stage. Once the butter and sugar are fluffy, reduce the mixer speed before gradually incorporating the oil and remaining wet ingredients.

Adding Oil, Eggs, Vanilla, and Sour Cream

With the mixer running on low speed, slowly pour in the ½ cup of vegetable or canola oil. Scrape down the bowl and mix again until it is fully incorporated. Add the four large eggs two at a time rather than all at once. Follow with one tablespoon of vanilla extract, scrape the bowl again, and then mix in the ½ cup of full-fat sour cream.

Scraping the sides and bottom of the mixing bowl between stages is important because unmixed butter or other ingredients can collect around the bowl. A uniform batter produces more consistent cake layers. Mixing gradually also reduces the chance of overworking the batter later, when the flour is added. Once the wet ingredients are properly combined, the dry ingredients can be introduced.

Adding the Dry Ingredients

The cake batter contains 2½ teaspoons baking powder, ½ teaspoon baking soda, one teaspoon kosher salt, and 3¼ cups all-purpose flour. The baking powder and baking soda should be fresh enough to work effectively. Old leavening agents can lose strength over time and may prevent a cake from rising as expected.

After distributing the baking powder, baking soda, and salt through the mixture, add half of the flour and mix only until partially incorporated. Pour in the buttermilk and mix roughly, then add the remaining flour. Continue mixing just until the batter becomes smooth and combined. Avoid unnecessary prolonged mixing once the flour has been incorporated, as gentle handling helps maintain a tender cake texture.

Why Buttermilk Is Used

One cup of buttermilk provides moisture and acidity to the Funfetti Cake batter. The acidity works particularly well with baking soda and contributes to the cake’s tender texture. Buttermilk also gives the batter enough liquid to incorporate the substantial amount of flour while adding a subtle flavor that balances the sweetness of the sugar and vanilla.

If buttermilk is unavailable, the source provides a homemade alternative. Measure one cup of milk minus one tablespoon, then add one tablespoon of white vinegar or lemon juice. Stir and leave the mixture for approximately ten minutes before using it. However, because your instruction is to preserve the original recipe ingredients, the recipe card below retains buttermilk as specified rather than replacing it.

Choosing the Right Sprinkles

The type of sprinkle used inside Funfetti Cake makes an important difference. Rainbow jimmies—the longer, narrow type of sprinkle—are recommended for the cake batter. They tend to hold their shape and color better during mixing and baking. The recipe specifically uses ¾ cup rainbow jimmies, providing enough colorful pieces to distribute throughout all three cake layers.

Tiny round nonpareils are less suitable inside the batter because their colors can bleed more easily, potentially creating a muddled appearance instead of separate colorful spots. The outside of the cake provides much more freedom. The additional ½ cup of decorating sprinkles can be used to create the appearance you prefer once the cake has been covered in vanilla buttercream.

How to Fold Sprinkles Into the Batter

After the cake batter is mixed, use a rubber spatula to scrape around the bottom and sides of the bowl. This final hand mixing helps catch any flour or batter that may not have been fully incorporated by the mixer. Once the batter is uniform, gently fold in the ¾ cup of rainbow jimmies until they are distributed throughout.

Avoid excessive stirring after adding the sprinkles. The goal is simply to spread them throughout the batter while minimizing color bleeding. Divide the finished batter evenly among the prepared cake pans and level the surface. Similar amounts of batter in each pan will produce layers of approximately equal thickness, making the finished stacked cake easier to assemble and more attractive when sliced.

Choosing the Correct Cake Pans

The recipe is designed primarily for three 9-inch round cake pans. Grease the pans and line their bottoms with parchment paper before adding the batter. This combination makes it much easier to release the baked cakes cleanly. Cake strips can also be wrapped around the pans if available to encourage more even baking.

Three 8-inch pans can also be used, but the original instructions caution against filling them too high. Approximately one cup of batter should be left out when using the smaller pans because overfilling may cause the centers to sink. The recipe therefore works most straightforwardly with three 9-inch pans, which can accommodate the intended quantity of batter.

Baking the Funfetti Cake Layers

Preheat the oven to 350°F before preparing the pans and batter. Once the batter has been evenly divided, bake three 9-inch cakes for approximately 30 to 35 minutes. If using 8-inch pans, allow approximately 35 to 40 minutes. Oven performance varies, so use the stated times as a guide and check the centers before removing the cakes.

Insert a toothpick into the center of a layer. When it comes out clean, the cake is ready. Allow all three layers to remain in their pans for approximately 30 minutes after baking. This resting period gives the warm cakes time to firm slightly, making them easier to remove without breaking or damaging their edges.

Cooling the Cake Before Frosting

After 30 minutes, carefully run a knife around each pan’s edge and turn the cakes onto a cooling rack. Peel away the parchment paper. If you plan to assemble and frost the cake the same day, transfer the layers on their cooling rack to the refrigerator and chill them completely for approximately one hour.

Fully cooled cake is considerably easier to frost than warm cake. Applying buttercream while the layers are still warm can soften or melt the frosting and make assembly difficult. If preparing the layers a day ahead, let them cool at room temperature for about an hour, wrap them in plastic wrap, and refrigerate overnight until you are ready to assemble the cake.

Easy Homemade Vanilla Buttercream

The vanilla buttercream requires only four components: unsalted butter, powdered sugar, vanilla extract, and milk. Begin by beating 1½ cups of room-temperature unsalted butter until smooth. Gradually mix in five cups of powdered sugar, adding approximately one cup at a time. Slow, gradual incorporation helps produce a smooth frosting while making the large quantity of powdered sugar easier to manage.

As the frosting begins to thicken, add one tablespoon of vanilla extract and two tablespoons of room-temperature milk. Continue mixing until creamy. If the finished buttercream remains too thick for comfortable spreading, add the third tablespoon of milk specified by the recipe. The ideal consistency should be firm enough to remain on the cake but soft enough to spread smoothly.

How to Assemble a Three-Layer Funfetti Cake

Once the cake layers are completely cold, place the first layer on a cake plate or serving board. Spread a thin layer of vanilla buttercream evenly across the top. Add the second cake layer and another thin coating of frosting, followed by the final cake layer. Keeping the filling layers reasonably thin reserves enough buttercream to cover the outside properly.

Next, apply a very thin crumb coat over the entire cake. A crumb coat traps loose cake crumbs and prevents them from appearing in the final frosting layer. Refrigerate the crumb-coated cake for approximately 20 minutes. Once the coating has firmed, spread the remaining vanilla buttercream over the top and sides to create the finished exterior.

Decorating With Rainbow Sprinkles

Apply the decorating sprinkles while the final buttercream is still fresh enough for them to adhere. You can scatter them across the top, press them onto the sides, create concentrated clusters, or combine different sprinkle shapes for a colorful finish. The recipe provides ½ cup of sprinkles specifically for decoration, separate from the ¾ cup of rainbow jimmies baked inside the cake.

For a scattered design, begin with a larger concentration of sprinkles near the top center and create smaller groups around the surface. When applying sprinkles to the sides, gently press them against the buttercream so they remain attached. Working over a large baking sheet can also catch loose sprinkles and make cleanup easier.

Perfect Cake for Birthdays and Celebrations

Few desserts communicate celebration as clearly as a colorful sprinkle cake. The three layers make this recipe substantial enough for a birthday table, while the rainbow interior gives every sliced portion an attractive appearance. The original recipe produces approximately 12 slices, making it appropriate for a family celebration or small party.

Although Funfetti Cake is strongly associated with birthdays, it can work equally well for anniversaries, graduation parties, children’s celebrations, or any occasion that calls for a colorful homemade dessert. Different decorating arrangements can change the appearance without changing the cake itself. Keeping the frosting white also provides a clean background that allows the rainbow sprinkles to stand out.

How to Store Funfetti Cake

A whole, unsliced cake can be refrigerated uncovered for about one day according to the source recipe. For longer storage, place it in a cake container to protect it from drying out. The source recommends approximately three days in the refrigerator for maximum freshness when the cake remains intact.

Once the cake has been sliced, protect the exposed surfaces carefully. Individual slices can be transferred to an airtight container, or the remaining cake can stay in a cake container with plastic wrap pressed against the cut sections. The source states that properly stored sliced cake can remain refrigerated for up to five days. Allowing a refrigerated slice to lose some of its chill before serving can also soften the buttercream.

Notes

Room-temperature ingredients are particularly important in this recipe. Bring the butter, eggs, sour cream, buttermilk, and buttercream milk to room temperature as specified before beginning. Cream the butter and sugar thoroughly before introducing the remaining ingredients, and avoid excessive mixing after the flour has been incorporated.

Use rainbow jimmies inside the cake batter because they are less likely to bleed than tiny round nonpareils. Decorative sprinkles on the outside can be selected more freely. Always add exterior sprinkles while the buttercream is fresh enough to hold them securely.

For the easiest preparation, use three 9-inch round cake pans. If three 8-inch pans are used instead, do not put all of the batter into them. The original method recommends leaving out approximately one cup to prevent overfilling and sinking in the centers.