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