Bring a pot of lightly salted water to a boil. Cook pasta for 8 to 10 minutes, or until al dente; drain, and rinse in cold water. Preheat oven to 180 degrees C.
In a frypan, cook onion in butter over medium heat until tender. Remove from heat and stir in cream cheese, cottage cheese, egg, basil, and salt and pepper.
In a medium bowl, mix together the soup, milk, wine, crabmeat, and prawns.
Lay 3 cooked sheets lasagne on the bottom of a 20x30cm baking dish. Spread 1/3 of the onion mixture over the noodles. Then spread 1/3 of the soup mixture over the onion layer. Repeat the noodle, onion, soup layers twice more. Top with Cheddar cheese and Parmesan cheese.
Bake in preheated oven for 45 minutes, or until heated through and bubbly.