1/2 cup peanut butter creamed together with 1/3 cup butter. Add 1 cup granulated sugar and 1/4 cup brown sugar. Beat in 2 eggs. Add 1 cup flour, 1 teaspoon baking powder and 1/4 teaspoon salt. Add 1/2 teaspoon vanilla and 6 ounces chocolate chips. Spread in a 9 inch square pan, buttered and bake at 350 degrees for 30 minutes. These brownies are moist and chewy.