Preheat oven to 350 degrees
In a medium bowl add the melted butter, 1 cup flour, and 1/4 cup powdered sugar - mix together completely
Press into the bottom of a glass 8x8 pan
Bake for 20 minutes
In another medium bowl, whip the 2 eggs until creamy
Add 1 cup white sugar, 2 TBS lemon juice, 2 TBS lemon zest, baking powder, and salt - whisk together until mixed completely
Remove pan from oven and pour lemon - sugar over the top
Bake for 20 to 25 minutes until top is golden and when touched the indent stays
Cool for 5 minutes
Sprinkle with the additional 1/4 cup powdered sugar
Cool and cut into 1 inch squares