Preheat the oven to 325°F (163°C). Line two baking sheets with parchment paper.
In a large bowl, cream together the softened unsalted butter and granulated sugar until light and fluffy, about 3-4 minutes.
Add the vanilla extract and mix until combined.
In a separate bowl, whisk together the all-purpose flour and salt.
Gradually add the flour mixture to the butter mixture, mixing on low speed until the dough just comes together.
Divide the dough into two equal portions. Roll each portion between two sheets of parchment paper to about 1/4 inch (6 mm) thickness.
Remove the top parchment paper and use a round cookie cutter (about 2 inches / 5 cm diameter) to cut out cookies. Place the cookies on the prepared baking sheets.
Use a smaller round cutter (about 1 inch / 2.5 cm diameter) to cut out the center of half of the cookies to create a window for the filling.
Gather the dough scraps, re-roll, and cut additional cookies as needed.
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 completely on the baking sheets.
Once cooled, spread about 1 teaspoon of raspberry jam on the whole cookies (without the cut-out center).
Top each jam-covered cookie with a cookie that has the cut-out center, gently pressing to sandwich them together.
Dust the assembled cookies with powdered sugar if desired before serving.