Cook the lasagne in a large pot of boiling salted water until al dente. Drain.
Saute onion in the butter or margarine. Combine the cottage cheese, cream cheese, basil, salt, pepper, egg and sauteed onion. Set aside.
Combine the mushroom soup, milk and garlic. Stir in the white wine, scallops, flounder fillets and prawns. Set aside.
Assemble ingredients in a greased lasagne pan as follows: a thin layer of seafood sauce, 1/5 noodles, 1/2 cheese mixture, 1/5 noodles, 1/2 seafood mixture, 1/5 noodles, 1/2 cheese mixture, 1/5 noodles, 1/2 seafood mixture, and remaining noodles. Place mozzarella cheese and Parmesan on the top.
Bake at 180 degrees C for 45 to 60 minutes. Remove from oven, and allow to stand for 10 minutes.