01 - Preheat the oven to 400°F. Grease a 2-quart baking dish with butter or cooking spray.
02 - Bring a large pot of salted water to a boil. Cook the macaroni until just al dente according to package directions. Drain well and set aside.
03 - In a large saucepan, melt 3 tbsp butter over medium heat. Whisk in the flour and cook for 1 minute, stirring constantly to form a smooth roux.
04 - Gradually whisk in the milk, stirring continuously to prevent lumps. Cook for 4–5 minutes until the sauce thickens slightly and coats the back of a spoon.
05 - Remove from heat. Stir in cheddar, Gruyère, and Parmesan until fully melted and smooth. Add Dijon mustard, smoked paprika, salt, and pepper to taste.
06 - Gently fold the cooked macaroni and chopped lobster meat into the cheese sauce until evenly distributed.
07 - Pour the mixture into the prepared baking dish, spreading it into an even layer.
08 - In a small bowl, combine breadcrumbs, melted butter, and parsley. Mix until the breadcrumbs are evenly moistened.
09 - Sprinkle the breadcrumb mixture evenly over the mac and cheese.
10 - Bake for 20–25 minutes until the topping is golden brown and the sauce is bubbling around the edges. Let rest for 5 minutes before serving.