Cream the butter and sugar until light in the bowl of an electric mixer fitted with the paddle attachment. Combine the flour and salt and, with the mixer on low, add to the butter until just mixed. Dump the dough onto a well-floured board and gather into a ball. Flatten the dough with floured hands and press it into muffin sheet, building up a ¼ -1/2 inch edge on all sides. Chill.
Bake the crust for 12 to 15 minutes, until very lightly browned. Let cool on a wire rack. Leave the oven on.
For the filling
Whisk together the eggs, sugar, lemon zest, lemon juice, and flour. Pour over the crust and bake for 15 to 20 minutes, until the filling is set. Let cool to room temperature.
Chill and serve!
Notes
Recipe adapted from Ina Garten's Lemon bars
Recipe by Naive Cook Cooks at https://www.naivecookcooks.com/easy-simple-lemon-bar-muffin/