prepare the mornay sauce:take 500 ml hot bechamel, add 50 g. butter,100 ml cream and salt and pepper. Butter the scallop shells and decorate the edges with mashed potato. Sprinkle with melted butter. Slice the cooked scallops. Pour a little of the mornay sauce into the bottom of the shells. Place the Sliced scallops on top of the sauce. Cover with more mornay sauce. sprinkle with grated Parmesan cheese and melted butter. Gratinate under a salamander grill.Serve with fresh parsley