1. In a large skillet, sauté shrimp, crab meat, and diced white fish with butter, minced garlic, and onion until just cooked through and fragrant. Remove from heat and set aside. In a saucepan, melt butter and whisk in flour to create a roux. Gradually add heavy cream while whisking constantly until smooth and thickened. Stir in Parmesan cheese, salt, and pepper. Set aside. Bring a large pot of salted water to a boil and cook the lasagna noodles according to package instructions until al dente. Drain and set aside. In a baking dish, spread a thin layer of the creamy cheese sauce on the bottom. Layer noodles, followed by a mixture of ricotta and seafood, then drizzle more sauce and sprinkle mozzarella. Repeat layers until all ingredients are used, finishing with sauce and mozzarella on top. Cover the dish with foil and bake in a preheated oven at 375°F (190°C) for about 30 minutes. Remove the foil and bake an additional 10-15 minutes until bubbly and golden on top. Let it rest for 10 minutes before slicing and serving.