Place oven rack in middle of oven and preheat oven to 350.

Butter a 9 x 13 baking pan and line with parchment paper, leaving an overhang on sides.

Make crust:

In a medium bowl, combine the melted butter, sugar, vanilla and salt and stir until well blended. Gradually add the flour, stirring to incorporate.

Press the flour mixture evenly into prepared pan. Bake for 15-18 minutes or until the crust is lightly golden. Now prepare the filling.

In a medium bowl, whisk the sugar and flour until well combined. Add the room temperature eggs and lemon juice and whisk until well mixed. When the crust is baked pour the lemon filling over the hot crust. Place back in oven and turn the temperature down to 300 degrees. Continue baking for 20 to 25 minutes or until the filling is puffy on top and the center wobbles slightly if jiggled.

Let the bars cool completely on a wire rack, then refrigerate for at least three hours.

Cut into bars and if freezing wrap each bar in plastic wrap and then place in an airtight container and freeze for up to 4 months.

Thaw on counter for 30 minutes or in the refrigerator overnight before dusting with powdered sugar.

If not freezing, dust with powdered sugar when ready to serve.

Lemon bars should be served chilled.