Use a little whole wheat flour in these bars to add fiber and nutrients. A browned butter frosting tops this dessert.
Grease a 15x10x1-inch baking pan; set aside.
In a large mixing bowl, beat the butter with an electric mixer for 30 seconds. Beat in sugar, baking powder, baking soda and salt until combined. Add eggs, pumpkin, sour cream, milk, and vanilla; beat until combined. Add all-purpose and whole wheat flours; beat until combined. Stir in 1 cup nuts.
Spread mixture evenly into prepared baking pan. Bake in a 350 degree F oven about 25 minutes or until a wooden toothpick inserted near the center comes out clean. Cool in pan on wire rack.
Prepare Browned Butter Frosting; spread over cooled bars. If you like, sprinkle with additional nuts. Cut into bars. Makes 48 bars.