Cook the Pasta:
Bring a large pot of salted water to a boil. Add the pasta and cook until al dente according to the package instructions. Drain and set aside.
Prepare the Cheese Sauce:
In a large saucepan, melt the butter over medium heat. Add the flour and whisk continuously for about 2 minutes to form a roux.
Gradually whisk in the milk, ensuring no lumps form. Continue to cook, stirring constantly, until the mixture thickens and starts to bubble.
Reduce the heat to low and stir in the shredded cheddar, Gruyère, mozzarella, and Parmesan cheeses. Stir until the cheese is completely melted and the sauce is smooth.
Add the Dijon mustard, garlic powder, onion powder, salt, pepper, and cayenne pepper (if using). Mix well.
Combine the Pasta and Cheese Sauce:
Add the cooked pasta to the cheese sauce and stir to coat the pasta evenly.
Add the Seafood:
Gently fold in the chopped lobster, shrimp, and crab meat until well combined.
Prepare the Topping:
In a small bowl, mix the panko breadcrumbs with the melted butter and grated Parmesan cheese.
Assemble and Bake:
Preheat your oven to 375°F (190°C).
Transfer the macaroni and cheese mixture to a greased 9x13-inch baking dish or a similar-sized casserole dish.
Sprinkle the breadcrumb mixture evenly over the top of the macaroni and cheese.
Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and the sauce is bubbly.
Serve:
Remove from the oven and let cool slightly.
Garnish with chopped fresh parsley, if desired.
Serve hot and enjoy your luxurious Lobster, Crab, and Shrimp Macaroni and Cheese!