Preheat your oven to 350°F (175°C) and grease a 9×13 inch baking dish.

In a medium bowl, mix together the softened butter, 2 cups of flour, 1/2 cup of sugar, and salt until crumbly.

Press the mixture into the bottom of the prepared baking dish to form the crust.

Bake the crust in the preheated oven for about 15-20 minutes, or until lightly golden.

In another bowl, whisk together 1 cup of sugar and 1/4 cup of flour.

Add the eggs, lemon juice, and lemon zest to the sugar and flour mixture, and whisk until smooth.

Pour the lemon mixture over the baked crust.

Return the dish to the oven and bake for an additional 20-25 minutes, or until the filling is set.

Allow the bars to cool completely in the pan before cutting into squares.

For a twist on the classic, try adding a teaspoon of vanilla extract to the lemon filling for a hint of warmth. You can also sprinkle a bit of shredded coconut on top of the lemon layer before baking for added texture and flavor. If you prefer a more pronounced tartness, increase the lemon zest to 2 tablespoons. For a gluten-free version, substitute the all-purpose flour with a gluten-free flour blend. Remember to store any leftovers in an airtight container in the refrigerator to keep them fresh.