Into a bowl, start by adding the cottage cheese, 1 egg, the salt and the grated mozzarella cheese. Mix very well until combined.
On a table, roll out the puff pastry and spread this filling over it. Make sure to leave some space around the filling to prevent it from leaking when the dough is sealed.
Now, roll the dough into a log shape.
Then, cut the log into about 2 finger-thick round slices.
Grease the edges and the bottom of a medium baking tin with butter or margarine, transfer all the rolls to it. Make sure they don’t stick together - leave some space between each roll.
Now, beat an egg and brush it over each roll.
Place in a preheated oven at 180°C (356°F) and bake for 30 minutes.
Baking time may vary depending on the power of your oven.
Serve.