1-First Step: Prep and Bake the Cake Layers Start by preheating your oven to 350°F and preparing your pans. Grease, flour, and line the bottoms of three 8-inch round cake pans with parchment paper; if you have cake strips, use them to ensure even baking. Sift together 3¾ cups all-purpose flour (450g), 2½ teaspoons baking powder, and 1 teaspoon salt in a bowl to combine them evenly. This step is crucial for a uniform rise in your funfetti cake.

Next, in a large mixing bowl, beat 2⅓ cups granulated sugar (466g), 1 cup softened unsalted butter (227g), and ⅓ cup vegetable oil (80mL) until the mixture is smooth and creamy, which should take about 2-3 minutes. Add the 7 large egg whites, room temperature, in three parts, mixing on low speed until just combined after each addition to avoid overbeating. For dietary adaptations, if you’re making a vegan version, swap the egg whites here with aquafaba.

Then, beat in 1 tablespoon vanilla extract until the batter is fluffy. Alternately add the sifted flour mixture and 1⅓ cups buttermilk (320mL), starting and ending with the flour, mixing until just combined after each addition and scraping the bowl as needed. Gently fold in ⅔ cup rainbow jimmies (100g) to keep their colors vibrant. Divide the batter evenly among the pans, tap them on the counter to settle, and bake for 32 to 38 minutes, rotating after 20 minutes. Let the cakes cool in the pans for 10 minutes before transferring to wire racks.

2-Second Step: Make the Frosting Once the cake layers are cooling, prepare the frosting. In a large bowl, beat 1 pound unsalted butter (450g) and ½ teaspoon salt until soft and smooth, about 2 minutes. Gradually add 2 pounds powdered sugar (900g) while mixing on low speed to avoid a sugar cloud. For low-calorie options, consider a sugar substitute at this stage.

Add 3 to 4 tablespoons heavy cream, one tablespoon at a time, until you reach a creamy consistency, then beat in 1 tablespoon vanilla extract. Increase the mixer speed and beat until the frosting is light and fluffy, which takes about 3-5 minutes. This frosting can be adapted for vegan diets by using plant-based butter and cream.

3-Third Step: Assemble the Cake After the cake layers have cooled completely, place one layer on a serving stand. Spread 1 cup of frosting evenly over the top to the edge. Repeat with the remaining layers, stacking them carefully. For preferences like gluten-free, ensure all components are swapped accordingly.

4-Fourth Step: Decorate and Finish Reserve 1 cup of frosting in a piping bag fitted with a large open star tip. Spread the remaining frosting over the top and sides of the assembled funfetti cake. Press rainbow sprinkles along the bottom 2 to 3 inches of the sides for a festive touch. Pipe dollops of the reserved frosting around the top edge and garnish with additional sprinkles. This step adds the fun element that makes your funfetti cake perfect for celebrations.

5-Final Step: Serve and Enjoy Allow the cake to set for about 30 minutes before slicing. Each serving offers 1129 calories, with nutritional benefits like 7g of protein and 154g of carbohydrates. Serve it at room temperature for the best flavor, and consider pairing it with fresh fruit for a balanced treat. For more decorating ideas, check out our lemon blueberry muffins for complementary flavors.