Ingredients

4 large egg whites 

1 cup sugar 

Pinch salt 

3 sticks (1 1/2 cups) unsalted butter, softened 

1 teaspoon pure vanilla extract 

2 cups finely crushed cream-filled chocolate sandwich cookies (about 20 cookies) 

Preparation

In the heatproof bowl of an electric mixer, combine egg whites, sugar and salt over a pot of simmering water. Whisking constantly, cook until sugar and salt dissolve and mixture is warm to touch (about 160 degrees). Using the whisk attachment, beat mixture on low speed and gradually increase to high, beating until mixture is stiff and glossy, about 10 minutes. With mixer on low, add butter a few tablespoons at a time, then whisk in vanilla. Using paddle attachment, beat buttercream until air bubbles are gone and mixture is smooth. Gently fold in crushed cookies. Use immediately.