Heat oven to 350 degrees.
Measure flour by dipping method or by sifting. Blend flour, butter and confectioner's sugar thoroughly. Press evenly in 8x8 pan. Bake 20 minutes.
Beat rest of ingredients together. Pour over crust and bake 20 to 25 minutes more. Do not over bake (the filling puffs during baking, but flattens when cooled).
Note: if using Gold Medal Self-Rising flour, omit baking powder and salt. Makes 16 squares.