Put all ingredients into the food processor with steel cutting blade. Pulse on and off until a moist mixture forms. Press into a 9X13” baking pan and pierce with a fork. Bake in a 350 °F. oven for 12 to 15 minutes or until golden brown.
Meanwhile make the following filling. Remove the crust from the oven and pour in the filling. Return to the oven for 25 minutes. Cool slightly on a rack and sift over powdered sugar.
Cool completely and cut into squares.
Beat together in electric mixer until smooth and fluffy.