The tender shortbread crust in this recipe and the tart topping are a snap to make and the flavor is especially refreshing on a hot summer day. Be sure to use fresh lemons that are soft and fat. Roll them back and forth on the counter before squeezing to release their juices. For a margarita inspired treat, substitute limes for the lemons.Source: the Fat Witch Bakery
1Grease a 9 x 9" baking pan with butter. Dust with flour and tap out the excess. Preheat the oven to 350°.
To make the crust, sift the flour, powdered sugar, and salt into a bowl. Add the butter and mix into the flour, first with a fork and then finishing with your fingertips.
2Pat the mixture evenly into prepared baking pan and bake for 15 minutes or until golden. Allow the crust cool while you make the filling.
3To make the filling, beat the eggs until frothy. Slowly add the sugar, until just combined. Beat in the lemon juice and zest and combine well.
4Mix the flour and salt and then sift together directly into the filling mixture. Mix gently until they are incorporated into lemon mixture. Pour the filling over the baked crust and bake 15 minutes or until the top is set. It should have tiny bubbles on the surface and the edges should be Brown and slightly pulling away from sides.
Remove from the oven and cool on a rack for one hour.