Combine flour and 1/2 cup powdered sugar in a large mixing bowl; stir well. Cut in butter with a pastry blender until mixture resembles coarse meal. Spoon into a 13- x 9- x 2-inch baking dish; press firmly into bottom of dish. Bake at 350° for 20 minutes. Remove from oven.
Combine eggs, sugar, 1 tablespoon powdered sugar, and lemon juice; beat well. Pour egg mixture over hot crust. Continue baking at 350° for 25 minutes or until lightly browned. Let cool, and cut into 1 1/2-inch squares.