Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

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

Add the vanilla extract and mix until well combined.

In a separate bowl, sift together the all-purpose flour, cornstarch, and salt.

Gradually add the dry ingredients to the butter mixture, mixing until just combined and a dough forms.

Scoop out tablespoon-sized portions of the dough and roll them into balls. Place the balls onto the prepared baking sheet, spacing them about 2 inches apart.

Using your thumb or the back of a spoon, create a small indentation in the center of each dough ball.

Fill each indentation with a small amount of fruit jam, being careful not to overfill.

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

Remove the cookies from the oven and allow them to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.