Makes 24 bars
For the crust:
For the topping:
Preheat oven to 350 F. Generously butter a 9 x 13 pan and set aside.
To make the crust, mix together butter, flour, confectioners' sugar and salt in a food processor or electric mixer. Blend until combined fully and press into the bottom of the baking pan in an even layer. Bake for 15 minutes, until crust is just barely golden.
Leave oven on and allow crust to cool on wire rack while you prepare the topping.
In a food processor or in the bowl of an electric mixer fitted with the whisk attachment, combine eggs, sugar, lemon zest, lemon juice and flour until combined. Pour over cooled crust and bake for 25 minutes, until topping is just set.
Cool and dust with confectioners' sugar.