Whatever the reason, Italians use far less cheese than we drown our dishes in here but still the special salty favor perks up this traditional dish.
First I glossed the bottom of a baking dish with olive oil and bread crumbs. Then I layered in thinly sliced potatoes (freshly harvested from our garden), matchsticks of zucchini, sliced onions, parmesan, parsley and more bread crumbs drizzling as I went with olive oil, S&P. Next came a layer of mussels on the half shell. I tried to open them as I would an oysters but without good results so I resorted to steaming the mollusks for just a few minutes until they popped open and pulling the top shell. I topped the mussels with bread crumbs, parsley, parmesan, and olive oil and layered on the rest of the potatoes, onions, squash, and parsley -- still drizzling as I went with olive oil, S&P and adding a sprinkle of parmesan and breadcrumbs on top. I finished off the casserole with another layer of mussels, and still more parmesan, olive oil, bread crumbs, and parsley. Just before baking I drizzled in about 1 1/2 cup of the mussel cooking liquid and brought the covered pot up to a boil on the stove. I popped the casserole (still covered) into the oven for 35 - 40 minutes and then an additional 30 without the cover.
The results were tender soft potatoes that whispered of the sea, sweet mussels, and a delicate broth just right for thick slices of toasted bread.
It's not chef's food I guess. And probably not refined.
But as James said, "You can't get anything this good in a restaurant. . . I'm never taking you out to dinner."