Preheat your oven to 350°F (175°C).
Prepare your baking dish by greasing an 8x8 inch pan.
In a mixing bowl, combine flour, sugar, melted butter, baking powder, and salt.
Press the mixture into the bottom of the prepared pan.
Bake the crust for about 15 minutes, until lightly golden.
In another bowl, whisk together the eggs, granulated sugar, lemon juice, and lemon zest until smooth.
Pour the lemon filling over the pre-baked crust.
Bake for an additional 20-25 minutes until set.
Remove from the oven and allow to cool completely in the pan.
Dust with powdered sugar before slicing.
Slice into squares and serve.