Make the Shortbread Dough : In a large mixing bowl, cream the softened butter and sugar together until light and fluffy. Mix in the vanilla extract. Gradually add the flour, mixing until the dough comes together. Avoid overmixing to keep the cookies tender.

Prepare the Cookies : Divide the dough into two equal portions. Roll each portion into a rectangle about ¼ inch thick between two sheets of parchment paper. Spread a thin layer of raspberry jam evenly over one rectangle of dough. Carefully place the second rectangle on top of the jam layer, creating a sandwich.

Create the Swirls : Gently roll up the layered dough from one long edge to the other, creating a log. Wrap the log in plastic wrap and chill in the refrigerator for at least 1 hour, or until firm.

Slice and Bake : Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper. Remove the dough log from the refrigerator and slice into ¼-inch thick rounds. Place the rounds on the prepared baking sheet, spacing them about 2 inches apart. Bake for 12-15 minutes, or until the edges are lightly golden.

Add the White Chocolate Drizzle : Once the cookies have cooled, drizzle melted white chocolate over the tops using a spoon or piping bag for decoration. Allow the chocolate to set before serving.