Preheat the oven to 350°F. Spray a 9x13-inch baking pan with nonstick spray and line with parchment paper. Set aside.
Make the crust. Mix together the flour and powdered sugar in a large bowl.
2 cups all-purpose flour, ½ cup powdered sugar
Using your fingers, cut the butter into the mixture until it clings together and is crumbly.
1 cup salted butter
Press this mixture into the prepared pan and bake 20-25 minutes, until just turning golden.
While the crust bakes, make the filling.
In a large mixing bowl, use an electric hand mixer or whisk to beat together the eggs, sugar, and lemon juice. (If you love lemon, feel free to use a little more juice!)
4 large eggs, 2 cups granulated sugar, ⅓ cup lemon juice
In a separate bowl, stir together the flour and baking powder. Stir this mixture into the egg mixture. (This mixture will be very runny.)
½ cup all-purpose flour, ½ teaspoon baking powder
Once you’ve brought the crust out of the oven, pour this egg mixture over the baked crust.
Place the pan back into the oven and bake for approximately 25 minutes. It should be a light golden brown.
Remove it from the oven and allow it to cool before cutting and serving. Once your pan gets to room temperature, you might even want to pop it into the refrigerator for 5-10 minutes before cutting.
Lightly dust them with icing sugar (try using a fine sieve or sifter) to make them look extra fancy.