Measure the flour by gently spooning it into a cup, then sweeping off any excess.
Sift the flour, potato flour, and dry milk through a strainer.
Combine all of the dough ingredients and mix and knead to make a soft, smooth dough.
Place the dough in a lightly greased bowl, cover, and let it rise for 60 minutes.
Divide the dough into four equal pieces and shape each piece into a ball, covering them to rest for 15 minutes.
Roll one piece of dough into a 10" circle and brush with beaten egg.
Sprinkle with one-third of the cinnamon-sugar, leaving a ¼" border.
Repeat layering with the remaining dough pieces and filling.
Cut the layered dough into 16 equal strips and twist them to form a star shape.
Transfer the star to a baking sheet and let it rise for 45 minutes.
Preheat the oven to 400°F.
Brush the star with beaten egg and bake for 12 to 15 minutes until golden.
