Method: 1.Grease bottom of pan and preheat oven as directed on brownie box. 2.Prepare brownies as per instructions on box. 3.Add 1 teaspoon vanilla before mixing. 4.Fold in 1 cup of crushed chocolate sandwich cookies. 5.After brownies have cooled, they can be frosted. 6. Add 2 cups of powdered sugar and 1-1/2 teaspoons of vanilla to any brand of ready-made vanilla frosting. 7.Whip for 2 minutes. 8.Spread over top of brownies. 9.Top with remaining cup of crushed chocolate sandwich cookies.