The Very Best Lemon Triangles

Preheat the oven to 350 F

For the Crust:

In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar (part 1 only) until light and fluffy.

Combine the flour (part 1 only) and salt, and with the mixer on low, add to the butter until just mixed.

Press dough into a 9 x 13 x 2 inch baking dish, building up a 1/2 inch edge on all sides. Chill.

Bake the crust for 15 to 20 minutes until lightly browned. Let cool on wire rack. Leave the oven on.

For the Filling:

Whisk together the eggs, sugar (part 2 only), zest, lemon juice, and flour (part 2 only).

Pour over the crust and bake for 30 to 35 minutes until the filling is set.

Let cool to room temperature. Cut into triangles and dust with confectioners sugar (optional).