Use either fresh or dried morels for this recipe; if using dried, they must be soaked in cold water for at least 2 hours before using, which will bring them back to their original state. Dried are, however, not as good as fresh, although they cost about the same. Their flavour is a lot stronger and therefore you should reduce the quantity. Fresh morels will probably prove quite difficult to get but are well worth the effort. Also, if you do not wish to mess about with fresh clams, then cooked ones will do just as well. However, if using ready-cooked, then rinse them before adding them to the sauce as they are packed in brine and this will oversalt the finished sauce. Cockles can be used to achieve the same result.