Sieve Ricotta or cottage cheese into a mixing bowl. Beat together 4 tablespoons each melted butter and grated Parmesan, and 3 egg yolks, and stir into cheese alternately with flour. Season to taste with salt, and freshly ground black pepper and nutmeg.
Spoon the mixture into a pastry bag fitted with a large plain nozzle. Holding pastry bag over a large saucepan full of boiling salted water, force mixture through nozzle, cutting it in 1-inch pieces (gnocchi) with scissors. Cook gnocchi for 6 or 7 minutes; remove with perforated spoon and drain on a clean cloth.
When ready to serve, arrange gnocchi in overlapping rows in a well-buttered shallow casserole or gratin dish. Pour 6 to 8 tablespoons melted butter over them and sprinkle with remaining Parmesan cheese. Bake in a slow oven (350°-M3) for 10 minutes, and then brown under grill until golden. buttered baking dish with a layer of lasagne; remove half the meat balls from the Tomato Sauce with a perforated spoon, and spoon over lasagne; add a layer of diced Mozzarella cheese; sprinkle generously with grated Parmesan and crumbled Ricotta cheese, and moisten with well-seasoned Tomato Sauce. Repeat, using the same quantities, finishing with Tomato Sauce. Dot with butter and bake in a moderate oven (375°-M4) for about 30 minutes.