To make the crust

1. In the bowl of a stand mixer, cream the butter and sugar until light and fluffy. In a separate bowl, combine the flour and salt. With the mixer on low, slowly add the flour mixture to the butter and sugar mixture until just mixed. The mixture will resemble large, soft crumbs.
2. Pour the crumbs of dough into a 13x9x2-inch baking pan (glass works best for us) and press the dough evenly into the bottom of the pan, making the dough as smooth as possible and building up a ½ inch edge on all sides.
3. Chill the dough.
4. While the dough is chilling, preheat the oven to 350 degrees.
5. Once the oven has preheated, bake the crust for 15 to 20 minutes or until the crust is very lightly browned. Remove from the oven and let cool. Keep the oven on.

To make the filling

1. While the crust is baking, make the filling as follows:
2. Mix together the eggs, sugar, lemon zest, lemon juice, and flour. Mix until well combined.
3. Pour the filling mixture over the baked crust and then bake for 25 to 30 minutes until the filling is set.
4. Let cool completely. (We found it easiest to cut these bars if they were refrigerated for a few hours before cutting.)
5. Cut into 12 squares – then cut each square into triangles (either 24 or 48 smaller triangles).
6. Dust with confectioner’s sugar before serving.