Preheat oven to 375°F (190°C). Cook lasagna noodles according to package directions, drain and set aside.
Heat olive oil in a skillet over medium heat. Sauté minced garlic until fragrant, about 1 minute.
Add shrimp and cook until pink and opaque, 3-4 minutes. Stir in crab meat, salt, black pepper, and red pepper flakes; cook 2-3 minutes. Remove from heat.
In a bowl, combine ricotta cheese, 1 cup mozzarella, 1/2 cup Parmesan, heavy cream, and chopped parsley.
Spread a thin layer of Alfredo sauce on the bottom of the baking dish. Layer noodles, one-third of the cheese mixture, one-third of the seafood, and drizzle with Alfredo sauce.
Repeat layering two more times, finishing with noodles and Alfredo sauce on top.
Sprinkle remaining mozzarella and Parmesan cheese over the top layer and add breadcrumbs for crunch.
Cover with foil and bake for 25 minutes. Remove foil and bake an additional 10-15 minutes until golden and bubbly.
Let lasagna rest 10 minutes before serving. Garnish with additional parsley if desired.