I've never found a recipe that uses a whole jar of peanut butter before! Have the milk ready because they are riiiiiiich but so good!
Peanut Butter Brownies
1 16-ounce jar Smucker's Natural Creamy Peanut Butter, divided
1-1/2 cups firmly packed brown sugar
3/4 cup butter or margarine, melted, divided
4 eggs, lightly beaten
1 cup all-purpose flour
1 teaspoon baking powder
Dash of salt
3 cups powdered sugar
1/2 teaspoon vanilla
3-5 tablespoons milk
Heat oven to 350° F. Combine brown sugar, 1-1/4 cups peanut butter and 1/2 cup butter in medium bowl; mix until smooth. Add eggs; beat until well mixed. Combine flour, baking powder and salt; stir into peanut butter mixture. Stir until well mixed. Pour into greased 13 x 9-inch baking pan.
Bake 25 to 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 tablespoons milk. Beat until smooth. Stir in milk until frosting is spreading consistency. Spread over brownies.
Tip: Stir in one cup peanut butter morsels or semi-sweet chocolate morsels if desired.
Makes two dozen.