Prepare the crust: Preheat the oven to 350°F (175°C). In a medium bowl, mix the flour, powdered sugar, and salt. Add the cold butter and use a pastry cutter or your hands to work the butter into the dry ingredients until the mixture resembles coarse crumbs. Press the mixture into the bottom of a greased 9×9-inch baking dish, ensuring an even layer. Bake the crust for 15-18 minutes, or until it is lightly golden brown. Remove from the oven and set aside to cool.

1. Prepare the filling: In a separate bowl, whisk together the granulated sugar, flour, baking powder, and salt. Add the eggs, lemon juice, and lemon zest, and whisk until the mixture is smooth and well combined.
2. Assemble the squares: Pour the lemon filling over the cooled crust, spreading it evenly with a spatula. Bake the squares in the oven for 20-25 minutes, or until the filling is set and slightly golden around the edges.
3. Cool and dust: Once baked, remove the pan from the oven and allow the Lemon Squares to cool completely at room temperature. Once cool, dust with powdered sugar before cutting into squares.
4. Serve: Slice the Lemon Squares into squares or bars and serve!