**Prepare the Dough:** In a large mixing bowl, beat the butter and sugar with an electric mixer until light and fluffy, about 2-3 minutes. Add the egg and vanilla extract, and mix until fully incorporated.

**Mix Dry Ingredients:** In a separate bowl, whisk together the flour and salt. Gradually add the dry ingredients to the wet mixture, mixing until a soft dough forms.

**Chill the Dough:** Divide the dough into two equal portions, shape each into a disk, and wrap in plastic wrap. Refrigerate for at least 1 hour or until firm.

**Roll Out the Dough:** On a lightly floured surface, roll out one disk of dough into a rectangle about 1/4-inch thick. Spread a thin, even layer of raspberry jam over the dough, leaving a 1/2-inch border around the edges.

**Form the Swirl:** Carefully roll the dough tightly into a log, starting from one long edge. Wrap the log in plastic wrap and refrigerate for at least 1 hour (or freeze for 30 minutes) to firm up. Repeat with the second portion of dough.

**Preheat the Oven:** Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.

**Slice and Bake:** Using a sharp knife, slice the chilled dough logs into 1/4-inch thick rounds. Arrange the cookies on the prepared baking sheets, spacing them about 2 inches apart. Bake for 10-12 minutes, or until the edges are lightly golden.

**Cool and Serve:** Let the cookies cool on the baking sheet for 2-3 minutes before transferring to a wire rack to cool completely.