preheat oven to 350

place 2 C flour in food processor. add butter and powdered sugar and pulse until mixture looks like coarse meal. press into the bottom of a 13 x 9 baking pan. bake 20-25 min.

beat eggs with a mixer. add sugar, blend well. add lemon juice and lemon rind; beat well. add baking powder and remaining flour, beat well. pour over hot crust (don't let it cool). bake 30-35 min. sprinkle top with additional powdered sugar