The Preparation
Preheat oven to 325°F.
Mix melted butter, sugar, GF flour, salt, and vanilla for the crust.
Press crust into a 9x13 pan. Poke holes with a fork.
Bake crust at 325°F for about 25 minutes.
While crust bakes, whisk together sugar, GF flour, eggs, and lemon juice for filling.
Pour filling onto hot crust immediately out of oven.
Bake at 325°F for 26 minutes.
Cool for 2 hours at room temperature, then refrigerate.
Dust with powdered sugar before serving.