We put butter and flour to undo, in a pan.
We roast the previous mixture well without getting burned, but picking up a bit of toasted color.
On the other hand we will put the milk to boil.
Once we have the hot milk and the toasted mixture, add the milk little by little into the flour and butter mixture, until it begins to boil again and has a thick texture.
Finally we will add the sauce tartufata a little to the taste of each, as they want more powerful or softer.
We will bathe the cannelloni with the tartufata béchamel sauce, we will add the grated cheese and we will put them to gratin at 220/230 degrees for about 10 minutes.