Spread 2-3 tablespoons of Béchamel sauce on the bottom of the baking dish. Pour the filling in a pastry bag without the tip and fill the Cannelloni pasta from top to bottom.
Place the stuffed pasta in the baking dish.
Roughly chop the Mozzarella and scatter all over the top of the pasta.
Pour the white sauce on top of the Cannelloni, covering completely the pasta also on the sides (otherwise it will not cook).
Evenly sprinkle a couple of tablespoons of Parmigiano cheese on top to make a nice crust.
Bake in the pre-heated oven at 200°C (400°F) for about 30 minutes (check also the pasta packaging for precise instructions as each pasta brand is slightly different).