Preheat the oven to 350°F (175°C)
Prepare a 13 inch by 9-inch rectangular baking pan with parchment, covering the bottom and sides, the height of the pan should be about 2 inches.
For The Shortbread Crust- Combine the butter and sugar into a mixing bowl of a stand mixer using the paddle attachment and mix at medium-high speed until the mixture is creamy, smooth and sugar is dissolved.
Add the 2 cups of all-purpose flour, salt, and vanilla extract, and mix on medium-low speed until a breadcrumb consistency is developed.
Transfer the shortbread dough into the baking pan and spread pressing firmly onto the bottom and side of the baking pan.
Place into the oven and bake for 15-20 minutes or until golden brown in color.
Make The Lemon Filling- Add the sugar and eggs into a medium-size bowl and beat together until well combined.
Add the lemon zest and juice and mix until well incorporated.
Combine the 1 cup with the egg mixture and mix using a whisk the lemon filling is smooth and without any clumps of flour.
Pour the lemon filling into the crust, and bake for 30-35 minutes. The filling will be slightly set in the middle.
Once baked, let it cool at room temperature for 50-60 minutes, then refrigerate for at least 2 hours adding the confectioner's sugar and serving.
Finish off by gently dusting the top of the lemon bars with confectioners icing sugar.
Enjoy!