Preheat oven to 350°. In a large bowl, beat butter and confectioners' sugar until blended. Gradually beat in 1-1/2 cups flour. Press onto bottom of a greased 13x9-in. baking pan. Bake 18-20 minutes or until golden brown., Meanwhile, in a small bowl, whisk eggs, sugar, lemon juice and remaining flour until frothy; pour over hot crust. , Bake 20-25 minutes or until lemon mixture is set and lightly browned. Cool completely on a wire rack. Dust with additional confectioners' sugar. Cut into bars. Refrigerate leftovers.