We are going to flatten the puff pastry into a rectangular shape. We immediately cut it into strips about 7 centimeters wide. We chop the walnuts without necessarily being very fine. We reserve these two ingredients.
Now we cut the chocolate into pieces that we put in a pot with the spoon of water. We leave it on the fire, at a very low intensity, so that it begins to melt. We add the crème fraiche and stir non-stop until it is like a slightly thick ganache.
We let cool a couple of minutes outside the fire. We cover the puff pastry strips with the chocolate ganache, we spread the nuts. Roll each puff pastry strip to form long sticks. We cut them now in two or three. We beat the egg with which we cover each stick. Bake at 180ºC for about 25 minutes.