Preheat: Heat the oven to 300°F and line a baking sheet with parchment paper.
Whip the whites: Beat 2 egg whites until stiff peaks form. With the mixer running, slowly spoon in the powdered sugar.
Add flavors: Fold in the lemon zest, then the vanilla, Amaretto or almond extract, salt, and cinnamon.
Add almond flour: Fold in 3 cups of almond flour, then add more a little at a time until the dough holds together. Add a splash of water if too dry.
Chill: Shape into a ball, wrap in plastic wrap, and refrigerate for 1 hour.
Roll and cut: Cut the dough in half. Roll out on a powdered-sugar-dusted surface to ¼ inch thick. Cut out stars and place on the baking sheet.
First bake: Bake 10 to 13 minutes at 300°F, until set but still pale. Cool completely.
Make the glaze: Beat the egg white and salt on low to medium, adding the powdered sugar a spoonful at a time, until thick and stiff. Spoon into a piping bag.
Lower the oven: Reduce the oven to 225°F.
Glaze: Pipe a small blob in the center of each cookie and spread it out to each point with a small spoon or knife.
Second bake: Bake on the lowest rack for 10 minutes at 225°F. Cool completely before storing.