01 - Preheat oven to 375°F. Grease a 2-quart baking dish with butter or cooking spray.
02 - Cook the macaroni in salted boiling water until just al dente according to package directions. Drain well and set aside.
03 - In a medium saucepan, melt 3 tbsp butter over medium heat. Whisk in flour and cook for 1 minute, stirring constantly to form a smooth roux.
04 - Gradually add milk and heavy cream, whisking constantly until smooth and no lumps remain. Simmer for 3–4 minutes until sauce thickens enough to coat the back of a spoon.
05 - Remove from heat. Stir in cheddar, Gruyère, Parmesan, Dijon mustard, smoked paprika, salt, and pepper until all cheese is melted and sauce is silky smooth.
06 - Fold in cooked macaroni and lobster meat until evenly distributed. Pour mixture into the prepared baking dish.
07 - Melt 2 tbsp butter in a skillet over medium heat. Add breadcrumbs and cook, stirring frequently, until golden brown, 2–3 minutes. Remove from heat and stir in parsley, chives, lemon zest, and garlic powder.
08 - Sprinkle breadcrumb mixture evenly over the macaroni and cheese, covering the surface completely.
09 - Bake for 20–25 minutes until the top is golden brown and sauce is bubbling around the edges. Let rest for 5 minutes before serving to allow the sauce to set.