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