Crust:
1 cube unsalted butter, room temperature
1/4 cup sugar
pinch of salt
1 cup flour
Filling:
3 large eggs
1-1/2 cups sugar
1-1/2 Tbl. lemon zest (takes about 2 large lemons)
1/2 cup freshly squeezed lemon juice
1/2 cup flour
Powdered Sugar (for dusting)
Preheat oven to 350 degrees. For the crust, mix butter and sugar together until light and fluffy. Add the flour and mix just barely until combined (this will be crumbly). Line square pan with parchment. Press crust mixture into bottom of pan. Bake the crust for about 15 min, until just starting to turn golden around the edges. Remove from the oven to cool.
For filling, mix together eggs, sugar, lemon zest, and lemon juice. Add flour and mix. Pour over the cooling crust and return to oven for about 30 more minutes, until filling has set. (Don't take it out when it's just golden around edges...bake longer.) Remove from the oven and cool at room temperature. Cut into squares and dust with powdered sugar.