Heat oven to 180ºC . (325 degrees Fahrenheit. for glass baking dish). Remove wrappers from peppermint patties. Grease 13x9x2-inch baking pan. In large bowl, stir together butter, sugar and vanilla. Add eggs; beat until well blended. Stir in flour, cocoa, baking powder and salt; blend well. Reserve 2 cups batter. Spread remaining batter in prepared pan. Arrange peppermint patties about 1 cm apart in single layer over batter. Spread reserved 2 cups batter over patties. Bake 50 to 55 minutes or until brownies begin to pull away from sides of pan. Cool completely in pan on wire rack; cut into squares. About 36 brownies. Hershey's is a registered trademark of Hershey Foods Corporation. Recipe may be reprinted courtesy of the Hershey Kitchens.