Preheat the oven to 350 degrees F (175 degrees C). 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.

Spread a thin layer of Alfredo mixture in a 9x13-inch baking dish. Layer lasagna noodles, ricotta mixture, Alfredo mixture, and shredded cheese in the dish. Repeat layers until all ingredients are used, ending with shredded cheese.

Bake in the preheated oven, uncovered, until bubbly and the cheese is melted, about 45 minutes. Cover and continue baking until heated through, about 15 minutes more.