Preheat your oven to 350°F (175°C).
In a large mixing bowl, cream together the softened butter, granulated sugar, and powdered sugar until light and fluffy.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
In a separate bowl, whisk together the flour and salt. Gradually add it to the creamed mixture, mixing just until combined.
Scoop tablespoon-sized portions of dough and roll them into balls. Place them on a baking sheet lined with parchment paper.
Using your thumb or a spoon, press down gently in the center of each dough ball to create an indentation.
Fill each indentation with about 1/2 teaspoon of jam.
Bake for 12-15 minutes, or until the cookies are lightly golden around the edges.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.