In a bowl, mix the flour, sugar, ground almonds, and butter by hand. Knead well to form a smooth ball of dough.
Preheat your oven to 410°F (210°C).
Shape the dough into moon crescent shapes (this is the most time-consuming step), and place them on a baking sheet lined with parchment paper. Bake the first batch while you prepare the second.
Bake for about 10 minutes. Remove the cookies from the oven before they brown.
Let them cool slightly, then remove the cookies from the baking sheet. Be careful, they are very fragile when hot.
Roll the crescents in a mix of cinnamon and powdered sugar. Enjoy.