. Prepare the dough:

• In a large bowl, cream the softened butter and sugar until light and fluffy. Add the egg and vanilla extract, mixing until smooth.
• Gradually add the flour, baking powder, and salt. Mix until just combined, forming a soft dough.

2. Chill the dough:

• Divide the dough into two equal portions. Flatten each into a rectangle, wrap in plastic wrap, and refrigerate for 30-60 minutes, or until firm.

3. Prepare the filling:

• If needed, mix the raspberry preserves with the cornstarch in a small saucepan over low heat. Stir until slightly thickened, then let cool completely.

4. Assemble the cookies:

• On a floured surface, roll one portion of the dough into a 9×12-inch rectangle. Spread half the raspberry preserves evenly over the dough, leaving a 1/2-inch border along the edges.
• Starting from the long side, carefully roll the dough into a tight log. Wrap the log in plastic wrap and refrigerate for at least 1 hour. Repeat with the second portion of dough.

5. Slice and bake:

• Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
• Remove the dough logs from the refrigerator and slice into 1/4-inch thick rounds. Place the cookies on the prepared baking sheets, spacing them about 1 inch apart.
• Bake for 10-12 minutes, or until the edges are lightly golden. Let cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.