1Preheat oven to 350. Make crust: cream 1/2 lb butter and 1/2 c sugar, 2 c flour and salt. Shape into a ball and press into 9x13x2" pan and 1/2" up sides. Chill 15 mins, then bake 15-20 mins til light brown.
2Make filling: whisk 6 eggs, 3c sugar, lemon zest, lemon juice and flour. Pour over crust and bake 30-35 minutes. Cool and sprinkle with powdered sugar.