Preheat the oven to 350°F (175°C).
In a large mixing bowl, cream together the softened butter and sugar.
Add the egg and vanilla extract to the creamed mixture, and mix until well combined.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined.
Chill the cookie dough for at least 30 minutes to firm up.
Scoop tablespoon-sized portions of dough and roll them into balls.
Place the dough balls on a lined baking sheet, spacing them about 2 inches apart.
Use your thumb or a spoon to create an indentation in the center of each ball.
Fill each indentation with your chosen fruit jam.
Bake in the preheated oven for 12-15 minutes, until the edges are lightly golden.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack.