Baked Shrimp Mac and Cheese

Cook Pasta: Cook the macaroni according to package directions, aiming for al dente (slightly firm). Drain and set aside.
Sauté Shrimp: In a separate skillet, heat the olive oil or butter over medium-high heat. Add the cleaned shrimp and season generously with Cajun or Old Bay seasoning. Cook for 2-3 minutes per side until they are pink and just cooked through. Set aside.

Make Roux: In a large saucepan, melt the butter over medium heat. Whisk in the flour and cook, stirring constantly, for 2 minutes to cook out the flour taste. This is the roux.
Add Milk: Slowly whisk in the warmed milk or half-and-half until the sauce is smooth. Bring the mixture to a gentle simmer, whisking frequently until the sauce thickens enough to coat the back of a spoon (about 8-10 minutes).
Season: Remove the thickened sauce from the heat. Stir in the Dijon mustard and nutmeg. Season with salt and pepper.
Add Cheese: Gradually add the shredded cheese blend, stirring constantly until all the cheese is completely melted and the sauce is smooth and luxurious.

Combine: Gently fold the cooked pasta and the seasoned shrimp into the prepared cheese sauce. Stir carefully to ensure everything is evenly coated.
Prepare Pan: Lightly grease a 9×13 inch baking dish. Pour the mac and cheese mixture into the prepared dish.
Create Topping: In a small bowl, mix the Panko breadcrumbs with 2 tablespoons of melted butter. Sprinkle this mixture evenly over the top of the mac and cheese.
Bake: Bake in a preheated oven at $190^\circ\text{C}$ ( $375^\circ\text{F}$ ) for 20-25 minutes, or until the topping is golden brown, the cheese is bubbly, and the casserole is heated all the way through.
Serve: Let the casserole rest for 5-10 minutes before garnishing with fresh chopped parsley and serving hot.