Preheat your oven to 350°F (175°C).
In a mixing bowl, combine flour and powdered sugar.
Add softened butter and mix until crumbly.
Press the mixture into the bottom of a greased 8x8 inch baking dish.
Bake the crust for 15 minutes until lightly golden.
In another bowl, whisk together eggs, granulated sugar, and lemon juice.
Add lemon zest, baking powder, and salt to the egg mixture.
Pour the lemon filling over the baked crust.
Bake for an additional 20 minutes until set.
Let cool and dust with powdered sugar before slicing into squares.