01 - Preheat oven to 375°F. Grease a 2-quart baking dish with butter or cooking spray.
02 - Bring a large pot of salted water to boil. Cook macaroni until just al dente, about 1 minute less than package directions. Drain thoroughly and set aside.
03 - In a medium saucepan over medium heat, melt 3 tbsp butter. Whisk in flour and cook for 1 minute, stirring constantly to form a smooth paste.
04 - Gradually whisk in milk and heavy cream, ensuring no lumps form. Bring to a gentle simmer and cook for 3–4 minutes, stirring frequently, until sauce thickens enough to coat the back of a spoon.
05 - Remove saucepan from heat. Stir in cheddar, Gruyère, Parmesan, Dijon mustard, smoked paprika, salt, and pepper until cheese is completely melted and sauce is smooth.
06 - Add cooked macaroni and chopped lobster meat to the cheese sauce. Gently fold until evenly distributed. Transfer mixture to the prepared baking dish.
07 - In a skillet over medium heat, melt 2 tbsp butter. Add breadcrumbs and toast for 2–3 minutes until golden brown, stirring frequently. Remove from heat and stir in parsley, chives, lemon zest, and garlic powder.
08 - Sprinkle the seasoned breadcrumb mixture evenly over the macaroni and cheese, covering the surface completely.
09 - Bake for 20–25 minutes until the top is deeply golden brown and the sauce is bubbling around the edges. Let rest for 5 minutes before serving to allow the sauce to set.