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The BEST White Sheet Cake (Doctored Cake Mix!)

Transform a mediocre boxed cake mix into a tall, super moist, bakery-worthy 9x13 cake that everyone will be asking the recipe for!

Course Dessert
Category Cake
Keyword cake
Prep Time 10 minutes
Cook Time 30 minutes
Total Time 30 minutes
Servings 24
Calories 207 kcal
Author Melissa Rose


9x13 White Cake

  • 1 15.25 ounce box white cake mix I prefer Pillsbury Moist Supreme
  • 1 cup all-purpose flour
  • 1/2 cup white sugar
  • 1 teaspoon vanilla extract
  • 1 1/2 cups water
  • 3/4 cup sour cream
  • 4 large egg whites (equal to 1/2 cup if using liquid carton egg whites)

Cream Cheese Frosting

  • 1/2  cup unsalted butter (softened)
  • ounces  cream cheese (softened)
  • 1 teaspoon vanilla extract
  • 1/4 teaspoon almond extract
  • 1 1/4 cup powdered sugar add more for stiffer frosting


  1. Preheat oven to 325°F.
  2. In a large bowl or stand mixer, whisk together cake mix, flour, sugar, and salt.
  3. Once incorporated, add in the vanilla, water, sour cream, and egg whites one at a time until combined. Do not whip cake mix, just mix until everything in incorporated.

  4. Pour batter into greased 9x13 metal pan and bake for 28-30 minutes or until toothpick or fork come out clean.

  5. Allow to cool completely before frosting.

To Make Cream Cheese Frosting:

  1. In a large bowl, beat the butter and cream cheese on medium speed using a hand or stand mixer (with paddle attachment) for 2-3 minutes (until light and creamy).

  2. Keeping the mixer on medium speed, slowly add in vanilla extract, almond extract and powdered sugar. Once incorporated, turn mixer to high speed and beat for 2 minutes until creamy.

  3. Spread on cooled cake and top with sprinkles!

  4. If not enjoying immediately or within 1-2 hours, refrigerate cake until serving.

Recipe Notes

  • Looking for a more pipe-able, fluffy frosting? Try my Buttercream Frosting recipe instead!
  • If you don't have almond extract you can substitute for extra vanilla or even lemon extract. Although I do think almond extract gives the best flavor!
  • You can turn these in cupcakes by baking for 18-20 minutes. Recipe yields 24 standard sized cupcakes.
  • I used and prefer Pillsbury White (Moist Supreme) but I’ve tried it with several other mixes and it works fine.
Nutrition Facts
The BEST White Sheet Cake (Doctored Cake Mix!)
Amount Per Serving (1 square)
Calories 207 Calories from Fat 72
% Daily Value*
Fat 8g12%
Saturated Fat 5g25%
Cholesterol 19mg6%
Sodium 213mg9%
Potassium 44mg1%
Carbohydrates 32g11%
Fiber 1g4%
Sugar 20g22%
Protein 2g4%
Vitamin A 226IU5%
Vitamin C 1mg1%
Calcium 62mg6%
Iron 1mg6%
* Nutritional information is estimated from a online calculator and can vary based on ingredients. Percent Daily Values are based on a 2000 calorie diet.