Preheat the oven to 350ºF. Line a glass 9x13 inch baking dish with parchment paper, allowing the paper to hang over.

In a mixing bowl, combine the flour, granulated sugar and salt. Add in the melted butter and vanilla extract. Stir with a spatula to combine, the dough will be thick. Press the dough into the prepared pan and bake for 20 minutes, until golden in color. Remove from the oven and use a fork to make small holes all over the crust. Be sure to not poke fully through the crust. This tip helps the filling stick to the crust.

Meanwhile, prepare the filling. In a mixing bowl combine the granulated sugar and flour. Add in the eggs and lemon juice, whisk until fully combined.

Pour the filling over the hot crust. Return to the oven and bake for 20-25 minutes.

Remove from the oven and allow the bars to cool to room temperature, about an hour. Then refrigerate the bars for 2 hours. Before serving, use the parchment paper to remove the bars from the pan. Dust with powdered sugar and use a sharp knife to cut into squares. To cut lemon bars cleanly, dip your knife in warm water, shake off the excess, and cut. Clean the knife off and re-wet for each cut.