Instructions

1. Toast hazelnuts in a dry skillet over medium heat for 5-7 minutes, stirring constantly until fragrant and skins begin to crack. Allow to cool, then rub between a clean kitchen towel to remove loose skins.
2. Finely grind cooled hazelnuts in a food processor until they reach a fine, sandy texture, being careful not to over-process into a paste.
3. In a large mixing bowl, cream softened butter and powdered sugar together until light and fluffy, using an electric mixer on medium speed for about 3 minutes.
4. Add egg yolk and vanilla extract to the butter mixture, beating until fully incorporated and smooth.
5. In a separate bowl, whisk together ground hazelnuts, all-purpose flour, and a pinch of salt.
6. Gradually add dry ingredients to the butter mixture, mixing on low speed until just combined and a soft dough forms.
7. Divide dough in half, flatten each portion into a disk, wrap in plastic wrap, and refrigerate for 1 hour to firm up.
8. Preheat oven to 350°F (175°C) and line two baking sheets with parchment paper.
9. On a lightly floured surface, roll out one disk of dough to 1/8-inch thickness. Use a round cookie cutter to cut out base cookies.
10. For the top cookies, use the same round cutter and then a smaller decorative cutter (like a star or heart) to create a window effect.
11. Transfer cookies to prepared baking sheets, spacing them 1 inch apart. Chill for 15 minutes to help maintain shape.
12. Bake cookies for 12-15 minutes, or until edges are lightly golden. Allow to cool completely on wire racks.
13. Dust the top cookies (with cut-out centers) with powdered sugar using a fine-mesh sieve.
14. Spread a thin layer of raspberry jam on the base cookies, leaving a small border around the edges.
15. Carefully place the powdered sugar-dusted top cookies onto the jam-covered base cookies, creating a sandwich.
16. Store cookies in an airtight container between layers of parchment paper for up to 5 days. The cookies will remain crisp and flavorful.