Step 1: Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper to prevent the cookies from sticking.

Step 2: In a large bowl, cream the softened butter and powdered sugar together until light and fluffy, about 2-3 minutes. You can use an electric mixer or mix by hand if you prefer.

Step 3: Add the vanilla extract and mix again until incorporated. Gradually sift in the flour and salt. Mix until a dough forms, but be careful not to overwork the dough.

Step 4: Divide the dough into two portions. Roll out the first portion of dough into a flat sheet (around 1/4-inch thick) on a lightly floured surface.

Step 5: Take the raspberry jam (or fresh raspberries) and gently heat it on the stovetop with lemon juice to make it easier to swirl. Once heated, spread a thin layer of raspberry jam on top of the dough, leaving a small border around the edges.

Step 6: Carefully roll the dough up into a log, then use a sharp knife to slice the dough into rounds, about 1/2 inch thick. Place each cookie on the prepared baking sheets, spacing them about 1 inch apart.

Step 7: Bake in the preheated oven for 10-12 minutes, or until the edges of the cookies are lightly golden. Let the cookies cool on the baking sheets for a few minutes before transferring them to wire racks to cool completely.