Name: Copycat Costco Vanilla Cake Recipe
Prep time: 25 min
Cook time: 30 min
Total time: 1 h 10 min
Cuisine: American
Ingredients: 2 1/2 cups plus 2 tablespoons cake flour; 1 1/2 cups plus 2 tablespoons granulated sugar; 1 tablespoon baking powder; 3/4 teaspoon fine salt; 3/4 cup unsalted butter, very soft; 4 large egg whites, room temperature; 1 large egg yolk, room temperature; 1 tablespoon vanilla extract; 1 cup buttermilk, room temperature; 2 tablespoons water; 2 tablespoons cornstarch; 1 cup unsalted butter, very soft; 1/2 cup vegetable shortening, room temperature; 4 cups powdered sugar; 1/2 teaspoon fine salt; 1 tablespoon vanilla extract; 3 to 4 tablespoons whole milk or heavy cream, room temperature; Copycat Costco Vanilla Mousse (prepared separately); Sprinkles for decoration

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Introduction

This Copycat Costco Vanilla Cake is a delightful treat that combines a moist, tender cake with smooth vanilla buttercream and a luscious mousse filling. Perfect for celebrations or anytime you crave a bakery-style dessert at home.

A slice of white layered cake on a white plate with blue floral patterns. The cake has two thick soft yellow sponge layers with a thin white cream layer between them. The top is covered with smooth white frosting and decorated with small blue icing details and colorful round sprinkles. A fork lifts a bite showing the light, fluffy texture of the cake and cream. The scene is set on a white marbled textured surface with a soft cream cloth in the background. Photo taken with an iphone --ar 4:5 --v 7

Ingredients

2 1/2 plus 2 tablespoons cake flour
1 1/2 cups plus 2 tablespoons granulated sugar
1 tablespoon baking powder
3/4 teaspoon fine salt
3/4 cup unsalted butter, very soft
4 large egg whites, room temperature
1 large egg yolk, room temperature
1 tablespoon vanilla extract
1 cup buttermilk, room temperature
2 tablespoons water
2 tablespoons cornstarch
1 cup unsalted butter, very soft (for buttercream)
1/2 cup vegetable shortening, room temperature
4 cups powdered sugar
1/2 teaspoon fine salt
1 tablespoon vanilla extract (for buttercream)
3 to 4 tablespoons whole milk or heavy cream, room temperature
Copycat Costco Vanilla Mousse (for filling)
Sprinkles (for decorating)

Instructions

Step 1: Preheat your oven to 350°F. Prepare two 8-inch cake pans by spraying with baking spray and lining the bottoms with parchment paper. Set them aside.
Step 2: In a large bowl, combine the cake flour, granulated sugar, baking powder, and salt.
Step 3: Using a mixer on low speed, gradually beat in the softened butter. The mixture will look sandy or soft depending on your climate; both are fine. Continue beating for 1 to 2 minutes, then scrape down the sides and bottom of the bowl.
Step 4: Add the egg whites one at a time, beating well after each addition, then beat in the egg yolk and vanilla extract.
Step 5: Gradually add the buttermilk in three parts on low speed, beating for 1 to 2 minutes after each addition until smooth.
Step 6: Divide the batter evenly between the prepared pans. Bake for 26 to 30 minutes until cakes are golden on top and a toothpick inserted comes out mostly clean with a few moist crumbs.
Step 7: Let the cakes cool in the pans for 5 minutes before inverting them onto wire racks to cool completely. Remove the parchment paper. If you plan to assemble the cake the next day, wrap cooled cakes in plastic wrap and refrigerate.
Step 8: To make the buttercream, whisk together water and cornstarch in a small bowl and set aside. In a large bowl, beat butter and shortening until light and fluffy (3 to 4 minutes), scraping the bowl as needed.
Step 9: Add the cornstarch mixture to the butter and shortening, mixing well. Slowly add powdered sugar on low speed, scraping the bowl as needed. Stir in salt and vanilla extract. If too thick, add milk one tablespoon at a time until desired consistency is reached.
Step 10: If the cake layers have domes, level them with a serrated knife. Secure the first cake layer on a cake board using a bit of frosting. Pipe a ring of frosting around the edge of this layer, then fill the center with the vanilla mousse.
Step 11: Place the second cake layer on top. Coat the entire cake with buttercream using an offset spatula, smoothing and removing excess frosting.
Step 12: Decorate with remaining frosting and garnish with sprinkles. Slice and enjoy your homemade Copycat Costco Vanilla Cake!

Tips & Variations

Use room temperature ingredients to help create a smooth, even batter and buttercream.
If you don’t have buttermilk, use 1 cup of milk mixed with 1 tablespoon lemon juice or white vinegar, let sit for 5 minutes.
For a different flavor twist, add a teaspoon of almond extract to the batter or buttercream.
Make sure to level the cake layers for a neat look and even stacking.

Storage

Store the assembled cake covered at room temperature for up to 2 days or refrigerate for up to 5 days. If refrigerated, let the cake sit at room temperature for 30 minutes before serving to soften the buttercream. Leftover cake can also be wrapped tightly and frozen for up to 2 months; thaw overnight in the fridge.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I use regular milk instead of buttermilk?

Yes, you can substitute buttermilk with regular milk mixed with a tablespoon of lemon juice or white vinegar. Let it sit for about 5 minutes to curdle before using.

How do I prevent the cake from drying out?

Make sure not to overbake the cake; check for doneness with a toothpick near the end of the baking time. Also, store the cake properly covered to maintain moisture.