In a large mixing bowl, combine the flour, ground almonds, ground pistachios, sugar, vanilla sugar, and a pinch of salt. Stir until well mixed.

Add the diced cold butter and the egg to the dry mixture. Knead with fingertips or a pastry cutter until smooth dough forms.

Wrap the dough tightly in cling film and chill in the refrigerator for about 30 minutes.

Preheat your oven to 175 degrees C (350 degrees F).

Roll out the chilled dough on a lightly floured surface to about 1 cm thick.

Cut out star shapes using a cookie cutter and place them on a lined baking sheet.

For optional filling, sprinkle ground pistachios and sugar on half the stars and top with a second star.

Bake for 10-12 minutes until lightly golden brown. Cool completely on a wire rack.

Mix powdered sugar with cinnamon and gradually stir in lemon juice or milk until a thick glaze forms.

Once cookies are cooled, cover them with the cinnamon glaze.

While the glaze is wet, sprinkle with small pistachio stars or chopped pistachios.

Optionally, sprinkle edible glitter or powdered sugar over the stars.