Step 1 A) Make a quick béchamel sauce: Step 2 1- Dilute the cornstarch in a little milk. Step 3 2- Bring the rest of the milk to a boil. Step 4 3- When it is very hot, pour the diluted Maizena and stir constantly with a whisk or wooden spatula until the mixture thickens. Step 5 4- Stop the fire at the first bouillons; add grated cheese and possibly butter and let cool. Step 6 B) Roll out the puff pastry to obtain 4 rectangles about 2 to 3 mm thick. Step 7 C) Garnish with the béchamel cooled on a half of rectangle leaving a small border. Step 8 Pass a little water on this border. Step 9 Fold the rectangle over the stuffing and stick by pressing the edges with a fork. Step 10 Brown with the egg, being careful not to run it on the edges; the puffing would swell less, make some cuts. Step 11 Bake in preheated oven (200 to 225 ° C) for 20 to 30 minutes. Author's note Possible variants: Add 100 g diced ham or parsley mushrooms to the stuffing.