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.
Add the vanilla extract to the butter and sugar mixture 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 until the dough just comes together. Do not overmix.
Divide the dough in half and shape each half into a disk. Wrap in plastic wrap and chill in the refrigerator for 15 minutes.
On a lightly floured surface, roll out one disk of dough to about 1/4 inch thickness.
Using a round cookie cutter (about 2 inches in diameter), cut out cookies and place them on the prepared baking sheets about 1 inch apart.
Repeat with the second disk of dough.
Using a smaller round cutter or a piping tip, cut out the center of half of the cookies to create a window for the filling.
Bake the cookies in the preheated oven for 20-25 minutes, or until the edges are lightly golden.
Remove the cookies from the oven and let them cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.
Once cooled, spread about 1 teaspoon of raspberry jam on the whole cookies.
Top each jam-covered cookie with a cookie that has the cut-out center, gently pressing down to sandwich them together.
Allow the filled cookies to set for 10 minutes before serving.