Preparation

• Heat oven to 350°F.
• Spray 2 (9-inch) round pans with cooking spray; dust with cocoa powder. Coarsely chop 7 cookies; set aside. Finely crush remaining cookies; place in medium bowl. Add flour, baking powder and soda; mix well.
• Beat egg whites in small bowl with mixer on high speed until stiff peaks form; set aside. Beat granulated sugar, 1/3 cup butter and egg yolks in large bowl with mixer until well blended. Add flour mixture, water, sour cream, melted chocolate and 1 tsp. vanilla; beat on medium speed 1 min. Gently stir in egg whites until well blended. Pour into prepared pans.
• Bake 25 min. or until toothpick inserted in centers comes out clean. Cool in pans 10 min. Remove from pans to wire racks; cool completely.
• Beat 1 cup powdered sugar with remaining butter and vanilla in large bowl with mixer until well blended. Add remaining powdered sugar alternately with milk, beating well after each addition. Reserve 1/2 cup frosting.
• Stack cake layers on plate, filling with remaining frosting and chopped cookies. Spread top with Chocolate Glaze. Let stand 10 min. Decorate with reserved frosting. Keep refrigerated.