Preheat the oven to 325°F (165°C). Line two baking sheets with parchment paper.
In a large bowl, cream together the softened 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 comes together and is smooth.
Roll the dough into a log about 2 inches in diameter. Wrap in plastic wrap and refrigerate for 30 minutes to firm up.
Remove the dough from the refrigerator and slice into 1/4-inch thick rounds. Place the rounds on the prepared baking sheets about 1 inch apart.
Using a small round cookie cutter or the end of a piping tip, gently press the center of half of the cookies to create an indentation for the filling, being careful not to cut through.
Bake the cookies in the preheated oven for 18-20 minutes, or until the edges are lightly golden.
Allow the cookies to cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.
Once cooled, spread about 1/2 teaspoon of raspberry jam onto the flat side of each unindented cookie.
Top each jam-covered cookie with an indented cookie, gently pressing together to form a sandwich.
Serve immediately or store as directed.