Bring a large pot of salted water to a boil. Cook the elbow macaroni according to package instructions until al dente. Drain and set aside.
In a medium saucepan, melt the butter over medium heat. Whisk in the flour and cook for about 1 minute, stirring constantly to form a roux.
Gradually add the milk to the roux, whisking continuously until the mixture thickens and is smooth, about 5 minutes.
Stir in the Dijon mustard, garlic powder, onion powder, and both cheeses until melted and well combined. Season with salt and pepper to taste.
Fold in the cooked macaroni and lobster meat until evenly coated with the cheese sauce.
Preheat your oven to 350°F (175°C). Transfer the lobster mac and cheese mixture to a greased 2-quart baking dish.
In a small bowl, combine the breadcrumbs with a tablespoon of melted butter. Sprinkle the breadcrumb mixture evenly over the mac and cheese.
Bake for 15-20 minutes, until the top is golden brown and bubbly.
Let the dish cool for a few minutes before serving. Garnish with chopped parsley.