- Heat oven to 350°F.
- Combine brown sugar, 1½ cups peanut butter and 1/2 cup butter in medium bowl; mix until smooth. Add eggs and beat until well mixed.
- Combine flour, baking powder and salt; stir into peanut butter mixture. Stir until well mixed.
- Pour batter into greased 13 x 9 inch baking pan.
- Bake 25–30 minutes or until brownies begin to pull away from sides. Cool on wire rack.
- Combine remaining peanut butter, remaining butter, powdered sugar, vanilla and three Tablespoon milk. Beat until smooth.
- Stir in additional milk, 1 teaspoon at a time, until frosting is spreading consistency. Spread over brownies.
per serving: 310 calories, 16g fat, 6g saturated fat, 50mg cholesterol, 200mg sodium, 36g carbohydrate, 1g fiber, 6g protein