In a small saucepan over medium heat, combine the raspberry jam, cornstarch, and lemon juice.

Stir continuously until the mixture thickens slightly, about 2-3 minutes.

Remove from heat and let it cool completely while you prepare the dough.

In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy (about 2-3 minutes).

Mix in the vanilla extract.

Gradually add the flour and salt, mixing just until combined. The dough should be soft but not sticky.

Divide the dough into two equal portions. Place one portion on a sheet of parchment paper and roll it into a rectangle about ¼ inch thick.

Spread half of the cooled raspberry swirl mixture evenly over the dough.

Roll the dough tightly into a log, starting from the longer side, using the parchment paper to help guide the roll. Repeat with the remaining dough and raspberry swirl.

Wrap each log in plastic wrap and refrigerate for at least 1 hour or until firm.

Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Remove the dough logs from the refrigerator and slice them into ¼-inch thick rounds.

Place the cookies about 1 inch apart on the prepared baking sheets.

Bake for 12-15 minutes, or until the edges are just lightly golden.

Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Serve as is or dust with powdered sugar for an extra festive touch.