Dissolve the flour in 1/2 cup milk. Heat the rest of the milk in a pot with the cinnamon stick and the lemon peel. When it comes to a boil, add the flour and mix well. Stir and allow to boil again. Remove from heat.
Place the sugar and the water in a pot and bring to boil. Cook for exactly 2 minutes on high heat. Then remove from heat.
Add the sugar syrup gradually to the milk and continue stirring.
Strain the mixture and allow to cool.
Grease a muffin tray with butter and dust with flour.
Roll the puff pastry lengthwise into a tight spiral and cut into 10-12 slices.
Place the slices into baking molds.
With your thumbs start pushing the center of the dough until it reaches the top where it should be thicker. The bottom should have a thinner layer of dough.
Bake in preheated oven at 250 C for 10-12 min.
Press with the back of a spoon and allow to cool.
Add the egg yolks in the milk mixture and whisk.
Fill the lined molds with the custard.
Place the tray in the oven, preheated at 250 C for 15-18 minutes.
Remove from the molds and serve warm or cold. Sprinkle icing sugar or cinnamon to taste.