1. Prepare the cookie dough

In a large bowl, beat the softened butter and powdered sugar until creamy. Add the egg yolk, vanilla extract, and lemon zest, if using. Mix until combined.

2. Add the dry ingredients

In a separate bowl, combine the flour, ground almonds, cinnamon, and salt. Gradually stir the dry ingredients into the butter mixture until a soft dough forms. Avoid overmixing.

3. Chill the dough

Divide the dough into two portions, flatten into discs, and wrap in plastic wrap. Refrigerate for 30–60 minutes until firm enough to roll.

4. Roll and cut the cookies

Preheat the oven to 180°C (350°F) and line baking trays with parchment paper. Roll the dough on a lightly floured surface to about 3–4 mm thick. Cut out an even number of cookies using Christmas-themed or round cookie cutters. Cut a small star or circle from the center of half the cookies to create the tops.

5. Bake the cookies

Arrange the cookies on the prepared trays, leaving a little space between them. Bake for 10–12 minutes, or until the edges are just lightly golden. Allow them to cool on the tray for 5 minutes, then transfer to a wire rack to cool completely.

6. Add the jam filling

Warm the jam slightly and stir until smooth. Spread a small amount over the flat side of each whole cookie. Place a cut-out cookie on top and gently press together to form a sandwich.

7. Dust and decorate

Dust the top cookies with powdered sugar, allowing the jam to show through the cut-out centers. Arrange the finished cookies on a festive serving plate.