Preheat your oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, allowing some overhang for easy removal.

In a medium mixing bowl, cream together the softened butter and sugar until light and fluffy. Gradually add the flour and mix until a crumbly dough forms. Press the dough evenly into the prepared pan, creating a compact layer.

Bake the crust in the preheated oven for 15-20 minutes, or until lightly golden. Remove from the oven and allow it to cool slightly on a wire rack.

In another mixing bowl, whisk together the eggs and sugar until well combined. Add the flour and whisk until smooth, then stir in the freshly squeezed lemon juice until fully incorporated.

Pour the lemon filling over the slightly cooled crust, spreading it evenly with a spatula.

Return the pan to the oven and bake for an additional 20-25 minutes, or until the filling is set and no longer jiggles in the center. The edges should be slightly golden.

Remove the pan from the oven and let the bars cool completely in the pan on a wire rack. Once cooled, refrigerate for at least 1 hour to set the filling further.

Using the parchment paper overhang, lift the bars from the pan and transfer to a cutting board. Slice into 12 even squares and dust with powdered sugar before serving.

Store leftover lemon bars in an airtight container in the refrigerator for up to 5 days. For longer storage, wrap individual bars in plastic wrap and freeze for up to 3 months.