9x13 White Sheet Cake

A square slice of vanilla cake with white frosting, decorated with piped frosting and colorful sprinkles, sits on a white plate with more sprinkles scattered around.

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A light, fluffy white cake baked in a 9x13 pan and topped with whipped vanilla buttercream. Made from scratch with 5 egg whites for a pale crumb and tender texture. Easy to make, easy to serve, and tested to work every single time.

Prep Time10

Cook Time35

Course: Dessert

Cuisine: American

Keyword: 9x13 white cake

Servings:

Author: Beth

Ingredients

Cake

2 ½ cups (300g) all-purpose flour
2 tsp baking powder
½ tsp baking soda
1 tsp salt
¾ cup (170g) unsalted butter room temperature
1 ¾ cups (346g) granulated sugar
¼ cup (50g) vegetable oil
5 large egg whites room temperature
1 cup (227g) sour cream
½ cup (113g) milk I used whole milk
1 Tbsp clear vanilla extract

Frosting *See Notes

1 ½ cups (339g) unsalted butter room temperature
1 Tbsp vanilla extract
⅛ tsp salt
4-6 cups (454–681g) powdered sugar
¼ cup heavy cream more as needed, can substitute milk

Instructions

Cake

Preheat the oven to 350ºF (180ºC). Spray a 9x13 inch pan with non-stick cooking spray. Set aside.
In a small mixing bowl combine the flour, baking powder, baking soda, and salt.
2 ½ cups (300g) all-purpose flour, 2 tsp baking powder, ½ tsp baking soda, 1 tsp salt
In a large mixing bowl combine the butter, sugar, and vegetable oil, beat using an electric mixer, 1-2 minutes until fluffy.
¾ cup (170g) unsalted butter, 1 ¾ cups (346g) granulated sugar, ¼ cup (50g) vegetable oil
Add in the egg whites, sour cream, milk, and vanilla extract. Beat with the electric mixer.
5 large egg whites, 1 cup (227g) sour cream, ½ cup (113g) milk, 1 Tbsp clear vanilla extract
Gradually add the flour mixture to the wet ingredients, mixing just until the flour is incorporated.
Pour the batter into the prepared pan and spread evenly with a spatula.
Bake for 32-39 minutes or until a toothpick inserted into the center comes out clean. Light pans take longer to bake than dark pans.
Allow the cake to cool completely before frosting.

Frosting

In a mixing bowl, combine the butter, vanilla extract and salt, beat using an electric mixer until fluffy, 1-2 minutes.
1 ½ cups (339g) unsalted butter, 1 Tbsp vanilla extract, ⅛ tsp salt
Gradually add 4 cups of powdered sugar mixing on low until combined.
4-6 cups (454–681g) powdered sugar
Add in ¼ cup of heavy cream, beating on high until the frosting is whipped and fluffy.
¼ cup heavy cream
Taste to determine if you want more powdered sugar.
Spread the frosting over the cake and decorate with sprinkles if desired.

Notes

If you want to pipe a frosting border around the cake like shown in the photos, you will need more frosting. I used a Wilton 32 piping tip. Use the following recipe:

2 ½ cups (565g) unsalted butter, room temperature
2 Tbsp vanilla extract
⅛ tsp salt
6-10 cups (681-1135g) powdered sugar
4-7 Tbsp heavy cream

Gluten-Free: Use a 1:1 gluten-free baking flour blend in place of all-purpose flour. I used King Arthur’s Measure for Measure Gluten Free Flour with great results.
To Store: Keep the frosted cake covered tightly with plastic wrap or a lid at room temperature for up to three days. The sour cream and oil in the batter keep it soft and moist the whole time.
To Make Ahead: Bake the cake and let it cool completely, then wrap tightly in plastic wrap and store at room temperature for up to 24 hours before frosting. The frosting can be made ahead and refrigerated for up to three days. Bring to room temperature and beat briefly before spreading.
To Freeze: Wrap the unfrosted cake tightly in plastic wrap, then again in foil, and freeze for up to two months. Thaw overnight on the counter and frost as usual.

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