In a large mixing bowl, combine the gluten-free flour blend and powdered sugar. Stir to blend.

Cut the softened butter into small chunks and add it to the bowl along with the egg yolk and lemon extract or zest. Mix until it begins to form a dough.

Transfer the mixture onto a clean surface and knead gently until fully combined. Add a teaspoon of water if too dry or more flour if too sticky.

Wrap the dough in plastic wrap and chill in the refrigerator for at least 2 hours or overnight.

Preheat your oven to 325°F (160°C).

Dust a clean surface with gluten-free flour, divide the dough, and roll one half out to about 3mm thick.

Cut out cookie shapes with cookie cutters, ensuring an equal number of tops and bottoms. Cut a small hole in the center of the top pieces.

Bake for 10-15 minutes or until lightly golden. Cool on the baking sheet for a few minutes before transferring to a wire rack.

Spread about ½ teaspoon of jam on each bottom cookie, place the top cookie over the jam, and press gently.

Optional: Dust with powdered sugar or erythritol before serving.