In a large mixing bowl, combine softened unsalted butter and powdered sugar. Using an electric mixer, beat on medium speed for 2-3 minutes until light and fluffy.

Add the vanilla extract and mix on low speed until fully incorporated.

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

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

Preheat your oven to 350°F (175°C) while the dough is chilling.

Once chilled, scoop about 1 tablespoon of dough, roll it into a ball, and make a small indentation in the center. Fill with 1 teaspoon of blueberry jam, and reshape the ball.

Place the shaped cookies onto prepared baking sheets, spacing them about 2 inches apart. Bake for 12-15 minutes or until the edges are lightly golden.

Allow the cookies to cool for about 5 minutes before rolling them in additional powdered sugar.