preheat oven to 350F
shortbread:
mix together 1 stick (1/2 cup) softened butter + 1/3 cup powdered sugar + 3/4 cup & 2 tbsp all purpose flour
press into a lined 8×8 dish
bake for 20 minutes
lemon filling:
whisk together 2 eggs + 1 cup granulated sugar + zest from 2 lemons + juice from 2 lemons (about 1/4 cup) + 1/2 tsp baking powder
pour filling over shortbread and bake for 23 minutes
let cool, cut into bars and sprinkle with powdered sugar