1-First Step: Preparation and Mise en Place: Gather your ingredients and preheat the oven to 350°F (177°C). Grease a 9×13-inch pan generously to prevent sticking. Measure out all items like the 2 and 1/2 cups of cake flour and softened butter so everything is ready to go.

2-Second Step: Mix the Dry Ingredients: Whisk together 2 and 1/2 cups of cake flour, 2 teaspoons of baking powder, 1/2 teaspoon of baking soda, and 1 teaspoon of salt in a bowl. Set this aside for later, as it forms the base of your batter and helps with rising.

3-Third Step: Cream the Butter and Sugar: Beat 3/4 cup of softened unsalted butter on high speed until it’s creamy, about 1 minute. Add 1 and 1/2 cups of granulated sugar and beat for 2 minutes until well creamed. Scrape the bowl as needed to ensure even mixing, which creates a light texture.

4-Fourth Step: Add Wet Ingredients: Beat in 4 large egg whites on high until combined, about 2 minutes. Then, add 3/4 cup of sour cream and 1 tablespoon of pure vanilla extract; the mixture might look curdled, but that’s okay. This step builds the moisture and flavor of the cake.

5-Fifth Step: Combine Dry and Wet Mixtures: On low speed, add the dry ingredients just until mixed. Slowly pour in 3/4 cup of whole milk while the mixer is on low to avoid lumps. Hand whisk if needed for a smooth batter, as overmixing can make the cake tough.

6-Sixth Step: Fold in Cookies: Gently fold in 1 and 1/4 cups of chopped chocolate sandwich cookies by hand. This keeps the cookies from breaking down too much and maintains their crunch in the final product. For more frosting ideas, check out our chocolate buttercream frosting recipe to enhance your baking skills.

7-Seventh Step: Bake the Cake: Pour the batter into the prepared pan and bake for 32 35 minutes, or until a toothpick inserted comes out clean. Let the cake cool fully on a wire rack before moving on, which takes about 1-2 hours and ensures the texture stays perfect.

8-Eighth Step: Make the Frosting: Beat 6 ounces of softened cream cheese until smooth, then add 3/4 cup of confectioners’ sugar and 1 teaspoon of pure vanilla extract. Beat until smooth, then slowly add 1 and 1/2 cups of cold heavy cream on low speed, and whip on high until stiff peaks form.

9-Ninth Step: Finish the Frosting: Set aside 1 cup of frosting for piping if you want decorations. Fold 1 cup of chopped chocolate sandwich cookies into the remaining frosting for added texture. This step makes the topping both creamy and crunchy.

10-Final Step: Assemble and Serve: Spread the frosting over the cooled cake and pipe a border with the plain frosting as desired. Serve right away or refrigerate for up to 1 day, bringing it to room temperature before enjoying. The total time is about 4 hours, including cooling, and it yields 12 servings for your gathering.