Preheat the oven to 350ยบ. Line a 9x13 baking pan with parchment paper, and spray lightly with cooking spray.
Using a mixer, cream the butter and sugar together.
Add the flour and salt to the creamed butter and mix until a thick dough forms.
Press the dough into the pan, pushing up to form a 1/2 inch crust on all sides. Try to make the crust even all around.
Bake the dough for 20-22 minutes, or until golden brown. Allow the pan to cool, then slip into the fridge to chill.
While the crust cools, add the eggs, flour, sugar, lemon juice and zest to a bowl and whisk until completely blended.
Once the crust is completely cooled, pour the lemon filling into the pan, on top of the crust.
Pop the pan back into the oven and bake for 30-35 minutes until the filling is set, and no longer jiggles.
Allow the bars to cool completely on the counter or pop the pan back into the fridge to chill and further set.
Once the bars are completely cool, cut into rectangles or squares and sprinkle with powdered sugar.
