This is an entry for reference later.
I was watching Rick Stein's Food Heroes on the Lifestyle Food channel on Foxtel pay-tv tonight. He made a vegetarian cannelloni with leeks.I like the bechamel sauce that he made to pour over the cannelloni. He also added cheese - provolone - to this recipe. I think you can use Parmesan instead.
You can also use this sauce for lasagne or baked pasta.