Preheat your oven to 375°F.

Bring a large pot of water to a boil. Add 1 tablespoon of salt and cook 1 lb of elbow macaroni or cavatappi pasta until al dente according to the package directions. Drain the pasta and set aside.

While the pasta cooks, heat 1 tablespoon of olive oil or butter in a large skillet over medium-high heat. Season the 1/2 lb shrimp, 1/2 lb scallops, and 1/2 lb crab meat with a pinch of salt and pepper. Sauté the seafood for 2-3 minutes, just until the shrimp turn pink and the scallops become opaque. Remove from heat and set aside, as the seafood will finish cooking in the oven.

In a large pot over medium heat, melt 4 tablespoons of unsalted butter. Whisk in 1/4 cup of all-purpose flour to form a roux. Cook for about 1 minute until it smells slightly nutty.

Gradually pour in 4 cups of warmed whole milk and 1 cup of heavy cream, whisking constantly to prevent lumps. Stir in 2 teaspoons of Dijon mustard, 1 teaspoon of Old Bay seasoning (or paprika with a pinch of cayenne), 1/2 teaspoon garlic powder, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Let the sauce simmer gently for 5-7 minutes until it thickens enough to coat the back of a spoon.

Remove the sauce from heat and stir in 2 cups of shredded sharp cheddar, 1 cup of shredded Gruyère (or Swiss), and 1/2 cup of grated Parmesan cheese until the cheese is fully melted and the sauce is smooth.

Combine the drained pasta and cheese sauce, then gently fold in the cooked seafood.

Transfer the mixture to a buttered baking dish. For the crispy topping, mix 1 cup of panko breadcrumbs with 2 tablespoons of melted butter and 2 tablespoons of Parmesan cheese, then sprinkle evenly over the pasta.

Bake in the preheated oven for 25-30 minutes until the dish is bubbly and the topping is golden. Let rest for 5 minutes before serving to allow the sauce to settle.