Preheat the oven to 350°F (175°C).

In a large bowl, cream together the softened butter and sugar until light and fluffy.

Add the vanilla extract and mix well.

In another bowl, combine the all-purpose flour, cornstarch, and salt. Gradually add this mixture to the butter mixture, mixing until just combined.

Roll the dough into small balls and place them on a baking sheet lined with parchment paper.

Flatten each ball slightly with a fork.

Bake for 12-15 minutes or until the edges are lightly golden.

Let cool, then dust with powdered sugar if desired.