Preheat oven to 350 degrees.
Grease and flour a 13x9"pan.
Cream together butter and brown sugar.
Beat in eggs until well mixed, and then beat in the maple syrup until blended.
Beat in flour and baking powder.
Spread batter evenly in pan.Bake at 350 degrees for 30 min., or until a wooden pick inserted in center comes out clean.Cool and cut into squares.