Melt the butter in a skillet until it begins to sizzle. Add the onions, peppers, and mushrooms and cook until the onions are translucent and the liquid from the mushrooms has cooked away.
Add the seasonings, clam juice and water and bring to a boil.
Remove from the heat and add enough bread crumbs to form a stuffing. Allow to cool.
Preheat oven to 350° F. Open clams and place on a baking sheet. Stuff each clam with a spoonful of the filling and bake 10-12 minutes, until heated through.�Serve immediately.