Preheat oven to 350 degrees F. Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain.

Heat oil in a large saucepan over medium heat. Sautee garlic and mushrooms until tender. Pour in 2 jars Alfredo sauce. Stir in shrimp, scallops and crabmeat. Simmer 5 to 10 minutes, or until heated through. In a medium bowl, combine ricotta cheese, egg and pepper.

In a 9x13 inch baking dish, layer noodles, ricotta mixture, Alfredo mixture and shredded cheese. Repeat layers until all ingredients are used, ensuring that there is shredded cheese for the top.

Bake uncovered in preheated oven for 45 minutes. Cover, and bake 15 minutes.