Description

A fast, moist, and festive birthday cake made with a yellow cake mix, sour cream, and rainbow sprinkles. Ready in under an hour with zero fancy skills required.

Ingredients

Scale

15.25 oz box yellow cake mix
1 cup (240g) full-fat sour cream
1/2 cup (120ml) vegetable oil
3 large eggs, room temperature
2 teaspoons vanilla extract
1/2 cup (60g) rainbow sprinkles (divided)
1/2 cup (113g) unsalted butter, softened
2 cups (240g) powdered sugar
2–3 tablespoons heavy cream
1/4 teaspoon salt
1 teaspoon vanilla extract (for frosting)

Instructions

Preheat oven to 350°F (175°C). Grease two 8-inch round cake pans with butter or non-stick spray.
Pour yellow cake mix into a large mixing bowl. Whisk briefly to break up clumps.
Add eggs, sour cream, oil, 2 teaspoons vanilla extract, and half of the sprinkles to the bowl.
Mix vigorously with a whisk for 2 minutes or a hand mixer on low for 1 minute until smooth and consistent.
Divide batter evenly between the two prepared pans.
Sprinkle the remaining half-cup of sprinkles evenly over the top of each batter layer.
Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Let cakes cool in pans for 10 minutes, then turn out onto a cooling rack to cool completely.
While cakes cool, beat softened butter until creamy. Add powdered sugar, salt, 1 teaspoon vanilla, and 2 tablespoons heavy cream.
Beat on medium-high speed for 2-3 minutes until fluffy. Add more cream if needed for spreadable consistency.
Place one cake layer on a serving plate, spread frosting on top, add second layer, and frost top and sides.
Serve immediately or store covered at room temperature for up to 3 days.

Notes

Use full-fat sour cream for moisture. Room temperature ingredients emulsify better. If sprinkles sink, toss them in a teaspoon of flour before adding to batter. Do not overbake to avoid dryness. Can be frozen for up to 2 months if wrapped tightly.

Prep Time: 15 minutes
Cook Time: 30 minutes
Category: Dessert
Cuisine: American

Nutrition

Serving Size: 1 slice
Calories: 320
Sugar: 32
Sodium: 280
Fat: 14
Saturated Fat: 7
Carbohydrates: 45
Fiber: 1
Protein: 3

Keywords: birthday cake, confetti cake, easy cake, box mix hack, quick dessert, party cake, vanilla cake