Preheat the oven to 350°F (175°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 mixture, mixing until just combined and a dough forms.
Divide the dough in half. Roll out one half on a lightly floured surface 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.
Roll out the second half of the dough and cut out the same number of cookies.
On half of the cookies, use a smaller round cutter or a small cookie cutter to cut out a center hole to create a window for the jam.
Place the cookies with the holes on the baking sheets.
Bake the cookies for 12-15 minutes or until the edges are lightly golden. Remove from oven and let cool completely on wire racks.
Once cooled, spread about 1/2 teaspoon of raspberry jam on the whole cookies.
Top each jam-spread cookie with a cookie that has the cut-out hole, gently pressing to sandwich them together.
Dust the assembled cookies with powdered sugar if desired before serving.