In a mixing bowl, cream together the softened unsalted butter and powdered sugar until light and fluffy, about 2-3 minutes.

Incorporate vanilla extract into the creamed mixture and beat for another 30 seconds.

In a separate bowl, whisk together all-purpose flour, finely ground almonds, and salt. Gradually add to the wet ingredients, mixing on low until just combined.

Wrap the dough in plastic wrap and refrigerate for at least 1 hour.

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

Roll the chilled dough into 1-tablespoon-sized balls, make a small indentation in each, and fill with blueberry jam before reshaping.

Place cookies on the baking sheet, spaced 2 inches apart, and bake for 12-15 minutes or until lightly golden.

Cool on the baking sheet for 5 minutes before rolling in powdered sugar.