Preheat the oven to 325°F (163°C). Line two baking sheets with parchment paper.
In a large bowl, cream the softened unsalted butter and granulated sugar together until light and fluffy, about 3-4 minutes.
In a separate bowl, whisk together the all-purpose flour and salt.
Gradually add the flour mixture to the butter and sugar mixture, mixing until just combined and a dough forms.
Divide the dough in half. On a lightly floured surface, roll out one half of the dough to about 1/4 inch thickness.
Using a round cookie cutter (about 2 inches in diameter), cut out half of the cookies. Place them on the prepared baking sheets.
With the remaining dough, roll out and cut out the same number of cookies. Using a smaller round cutter or a small tip, cut out a small hole in the center of each cookie. These will be the top cookies.
Place the baking sheets in the refrigerator for 10 minutes to chill the dough.
Remove the baking sheets from the refrigerator. Spoon about 1/2 teaspoon of raspberry jam onto each whole cookie (bottom cookie).
Place the cookies with the cut-out centers (top cookies) gently over the jam-topped cookies, pressing lightly to sandwich them together.
Bake the cookies in the preheated oven for 20-25 minutes, or until the edges are lightly golden.
Remove from the oven and allow the cookies to cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.