Preheat oven to 280 degrees F (140 degrees C) and line a baking sheet with parchment paper.
In the bowl of a stand mixer fitted with the whisk attachment, beat egg whites at high speed until soft peaks form. Add powdered sugar and mix until smooth. Set aside 1/3 cup of the meringue for glazing the cookies.
Switch to the paddle attachment and add vanilla sugar, cinnamon, and 3/4 of the ground nuts. Beat until combined, then add as much of the remaining ground nuts so that the dough hardly sticks anymore.
Dust the work surface generously with powdered sugar and roll out the dough to 0.4 inches (1 cm) thickness. Dust top with powdered sugar if needed. Cut out cookies with a star-shaped cookie cutter, and dip the cookie cutter in powdered sugar in between.
Transfer stars to the baking sheet and spread meringue on top of each cookie. Put a little bit in the middle of each cookie and spread it finely with a small knife or pastry brush.
Bake cookies in the lower third of the oven for about 15 minutes. The meringue top needs to stay white, and the cookies should still be soft and look slightly wet on the bottom.
Pull cookies with the parchment paper onto a cooling rack and let them cool completely.