Preheat oven to 375. Grease a 9 x 13 inch baking ban. Combine the flour, 2/3 cup of confectioners sugar, ground vanilla beans, and butter until it forms a dough. Pat evenly into the pan. Bake for 20 minutes until slightly golden. Remove from oven.
Whisk together the eggs, granulated sugar, flour, and lemon juice until frothy. Pour over the hot crust. Return to the oven and bake for 20 – 25 minutes or until light golden brown. Cool on a wire rack. Sift confectioners sugar over top, then cut into squares.