For the crust:

1. Preheat oven to 350°F. Line a 9×13 ceramic baking dish with parchment paper so it hangs over the long sides of the dish, or generously grease to pan if not using parchment paper. Set the dish aside.
2. In a large mixing bowl, beat the powdered sugar and butter until smooth. Gradually mix in the flour, about 1 cup at a time, then add the salt and vanilla extract. The mixture should be dry and crumbly but stick together when pressed with your fingers.
3. Press the mixture evenly into the parchment-lined baking dish to form a thick crust. Bake the crust for 20-22 minutes or until the edges are lightly browned.

For the filling:

1. While the crust is baking, rub the lemon zest into the sugar in a large bowl until it is fragrant. Add the eggs and whisk until combined. Slowly pour in the lemon juice while beating until thoroughly combined.
2. Add the pinch of salt and mix in the flour with the whisk. It’s okay if there are a few small clumps of flour, but make sure any large clumps are broken apart and mixed in.
3. When the crust comes out of the oven, use a fork to poke holes in it without going all the way through.
4. Carefully pour the lemon filling over the warm crust, and bake for 24-26 minutes or until the middle of the bars is just slightly jiggly.
5. Let the bars cool at room temperature for 1 hour before chilling in the refrigerator for at least 2 hours or until they are completely set.
6. Pull the bars out of the dish using the overhanging parchment paper, dust with some extra powdered sugar, slice into 2-inch squares, and serve chilled.