Preheat your oven to 350 degrees F (180 degrees C).
In a bowl, combine Butter (2/3 cup), All-Purpose Flour (1 1/2 cup), and Granulated Sugar (1/3 cup). Mix until they are well combined.
Spray an 8x8 baking dish with baking spray.
Add the mixture to the dish. Using your fingers or a spatula, smooth it out so you get a level, even distribution.
Place it in the oven and bake it for about 20 minutes until it’s golden and firm.
In a separate bowl, combine Egg (3), All-Purpose Flour (2 1/2 tablespoon), Granulated Sugar (1 cup), and Lemon (2). Mix until they are well incorporated.
Remove the dish from the oven and pour the lemon mixture over the top.
Place it back in the oven and bake it for an additional 25 minutes.
Take the lemon bars out and set them aside on a wire rack. Remember that the bars will firm up as they cool.
Dust the lemon bars with Powdered Confectioners Sugar (to taste). Cut them into squares, serve, and enjoy.