1. In a saucepan over medium heat, combine raspberries and powdered sugar. Stir and cook until berries break down and mixture thickens, about 10 minutes. Strain if desired and let cool.

2. In a large bowl, cream together butter and granulated sugar until light and fluffy.

3. Add egg yolk and vanilla extract to the butter mixture. Mix until fully combined.

4. In another bowl, whisk together flour, baking powder, and salt. Gradually add to the wet ingredients and mix until a dough forms.

5. Cover and chill the dough in the refrigerator for 30 minutes.

6. Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.

7. Roll dough into small balls and slightly flatten them on the sheet.

8. Bake for 10–12 minutes until edges are just golden. Cool completely.

9. Spread a small amount of raspberry filling on the flat side of one cookie, then top with another to create a sandwich.

10. Drizzle with melted white chocolate and allow to set before serving or storing.