How to Make Box Cake Better

If you love the reliability and ease of a box cake mix but still want that soft, homemade texture, this is the best of both worlds. The truth is, box sizes have changed over the years, which is why many old “cake mix hacks” now lead to dense or gummy cakes. This version is adjusted specifically for today’s box size (15.25 oz), so it bakes up light, fluffy, and dependable every time.

Prep Time10

Cook Time40

Additional Time30

Total Time1 20

Course: Dessert

Cuisine: American

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Servings: servings

Author: Beth

Ingredients

Cake

15.25 oz white cake mix
½ cup (60g) all-purpose flour
½ cup (99g) granulated sugar
¾ tsp salt
1 large egg
2 large egg whites
1 cup (236ml) whole milk skim or 2% is fine
⅓ cup (76g) sour cream
¼ cup (50g) oil vegetable oil, olive oil or avocado oil
1 tsp vanilla extract

Chocolate Buttercream

1 ½ cup (339g) unsalted butter room temperature
¾ cup (63g) natural unsweetened cocoa powder
3-4 cups (339-454g) powdered sugar
1 tsp vanilla extract
¼ tsp salt
2-4 Tbsp milk or heavy cream

Instructions

Cake

If your box of cake mix is NOT 15.25 oz, do not proceed. This recipe was updated in February 2026 to address feedback and improve the overall texture, creating a lighter, more tender cake.
Preheat the oven to 350ºF.
In a large mixing bowl combine the whole egg, egg whites, milk, sour cream, oil and vanilla extract. Whisk to combine, 30 seconds.
1 large egg, 2 large egg whites, 1 cup (236ml) whole milk, 1/3 cup (76g) sour cream, 1 tsp vanilla extract, 1/4 cup (50g) oil
Add in the dry cake mix, flour, granulated sugar and salt. Beat with an electric mixer for 30 seconds.
15.25 oz white cake mix, 1/2 cup (99g) granulated sugar, 1/2 cup (60g) all-purpose flour, 3/4 tsp salt
Spray a 9x13 inch pan with non-stick cooking spray. Pour the batter into the pan and bake for 27-37 minutes or until a toothpick inserted in the center of the cake comes out clean. Allow the cake to cool completely before adding frosting.

Chocolate Buttercream

Place room temperature unsalted butter in a mixing bowl. Use an electric mixer on medium and beat the butter for 1 minute, until whipped and fluffy.
1 1/2 cup (339g) unsalted butter
Add in the cocoa powder, 2 cups powdered sugar, vanilla extract, and salt beat again on low for 1-2 minutes, scraping down the sides of the bowl, until everything is incorporated. Add in the remaining 1-2 cups of powdered sugar (depending on taste).
3/4 cup (63g) natural unsweetened cocoa powder, 3-4 cups (339-454g) powdered sugar, 1 tsp vanilla extract, 1/4 tsp salt
Beat in 2 tbsp of milk or heavy cream. If needed add more to get your desired consistency.
2-4 Tbsp milk or heavy cream
Spread the frosting on top of the cooled cake.

Video

Notes

This recipe was updated in February 2026 to address reader feedback about a dense or gummy texture. Reviews dated before February 2026 refer to the original version and do not reflect the current recipe.

Nutrition