Preheat the oven to 325°F (163°C).
Line a 9×13 inch (23×33 cm) sheet pan with parchment paper, leaving an overhang on the sides for easy removal.
In a large mixing bowl, cream the softened unsalted butter and granulated sugar together until light and fluffy, about 3-4 minutes using an electric mixer on medium speed.
Add the vanilla extract and mix until combined.
In a separate bowl, whisk together the all-purpose flour and salt.
Gradually add the flour mixture to the butter mixture, mixing on low speed until just combined and a dough forms.
Transfer the dough to the prepared sheet pan and press it evenly into the pan, smoothing the top with your hands or the back of a spatula.
Using a fork, prick the dough all over to prevent bubbling during baking.
Optional: Score the dough into 24 even squares using a knife to make cutting easier after baking.
Bake in the preheated oven for 25 minutes, or until the edges are lightly golden but the center is still pale.
Remove from the oven and allow the shortbread to cool completely in the pan on a wire rack.
Once cooled, lift the shortbread out of the pan using the parchment paper overhang and cut along the scored lines into 24 cookies.
Serve and enjoy or store as directed.