Heat oven to 350°F. Spray bottom of 9-inch square baking dish with no-stick cooking spray; set aside.
Combine brown sugar, sugar, peanut butter and 1/3 cup Cinnamon Sugar Butter Spread in large bowl; beat at medium speed until creamy. Add eggs; continue beating until well mixed. Add flour and baking powder; beat at low speed just until mixed.
Spread batter into prepared pan. Bake 28-34 minutes or until edges are lightly browned and center is set. Cool completely.
Combine powdered sugar, 2 tablespoons Cinnamon Sugar Butter Spread and enough milk for desired drizzling consistency in small bowl. Beat at low speed until creamy. Drizzle over cooled bars.
Omit glaze and sprinkle bars with powdered sugar.