Bring a large pot of salted water to a rolling boil. Add elbow macaroni and cook until al dente, about 8–10 minutes. Drain and set aside.

In a skillet over medium heat, melt 1 tablespoon of olive oil or butter. Add shrimp and scallops, sauté for 2–3 minutes until opaque, season lightly with salt and pepper, then fold in crab meat.

In a saucepan, melt 4 tablespoons of unsalted butter over medium heat. Whisk in flour to create a roux, then gradually add warmed milk and cream while whisking until thickened.

Stir in Dijon mustard, seasonings, and shredded cheese until melted and creamy.

Fold the cooked pasta and sautéed seafood into the cheese sauce until well-coated.

Preheat oven to 375°F (190°C). Grease a baking dish and transfer the mixture into it. Mix panko breadcrumbs with melted butter and Parmesan, then sprinkle on top.

Bake for 20 minutes or until golden brown and bubbly. Let cool slightly before serving.