Pre-heat the oven to 160C(320F) fan-forced and line an oven tray with baking paper
Lay the pastry on the bench and cut it into 4 squares then cut each square into 4 triangles.
Spread each triangle with pesto.
Place a piece of prosciutto on top of each triangle.
Starting from the long side, roll each one up and pinch the ends together to form a crescent.
Lay them on the oven tray and brush with the egg or milk.
Sprinkle the parmesan over the top.
Bake the crescents for 12-15 minutes or until they are golden.
They can be served hot, at room temperature or can be frozen for up to 3 months after they have been cooked.