Lightly grease a 9x9 inch microwave-safe baking dish or line with parchment paper.
Whisk 1 cup of all-purpose flour, 3 tablespoons of powdered sugar, and 1 tablespoon of lemon zest together.
Stir in 6 tablespoons of melted butter.
Press crust into prepared dish.
Microwave for three minutes at 80% power. Check to make sure the crust is firm.
Set aside.
Beat 1 cup of granulated sugar, 2 tablespoons of lemon zest, 3 large eggs, and 1/3 cup of fresh lemon juice together.
Beat in 1 tablespoon of all-purpose flour, 1/2 teaspoon of baking powder, and 1/4 teaspoon of salt.
Pour the filling over the crust and microwave for three minutes at 80% power.
Let cool completely and refrigerate for several hours or overnight.
Cut into squares, dust with powdered sugar, and sprinkle with additional lemon zest if desired.
