Preheat oven to 250º F (120º C)

Please see NOTES for best results.

In a large bowl, combine half of the powdered sugar, the ground almonds and cinnamon and mix until well-combined. Set aside.

Beat egg whites in bowl with mixer until soft peaks form. Add the other half of the powdered sugar and continue to beat for another 2 or 3 minutes until thick and creamy.

Remove 1 cup (250 ml) of the beaten eggs and set aside in a covered container (I put it in a condiment dispenser for easy decorating).

Add the almond mixture to the rest of the egg white mixture and mix well, until a dough forms. It's important to note that due to the amount of egg white varying (size of egg used, etc.) you may need more almond flour to form a dough. Cover and put in the fridge for 20 minutes.

Place some parchment paper on the counter and sprinkle with powdered sugar, then place the dough on top and shape into a ball, then slightly flatten it.

Sprinkle some more powdered sugar on top and place another piece of parchment on top.

Roll out to 1/4" thickness, then cut out star shapes; re-roll the dough, to cut out more until it has been completely used.

Place on a parchment or silicone sheet lined cookie sheet, then cover the top with the reserved meringue mixture. Using a condiment bottle makes it very simple to decorate the tops of these cookies (and others; see NOTES). Continue until all the cookies are coated in meringue.

Bake in preheated oven for 30 minutes, then turn off the oven, open the door slightly and allow to dry out for another 10 minutes or so, before removing from the oven. Place the Zimtsterne on cooling rack to cool completely.