Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente. Drain the pasta in a colander and set aside.
In a medium saucepan, melt the butter over medium heat. Once melted, whisk in the flour and cook for about 1 minute until bubbly and slightly golden.
Gradually add the whole milk to the butter-flour mixture, whisking constantly to avoid lumps. Continue to cook, stirring frequently, until the mixture thickens and bubbles, about 5-7 minutes.
Reduce the heat to low. Stir in the cheddar cheese, Parmesan cheese, mustard powder, garlic powder, onion powder, salt, and pepper. Stir until the cheeses are fully melted and the sauce is smooth.
Combine the cooked macaroni with the cheese sauce and fold in the lobster meat gently until evenly mixed.
Preheat your oven to 350°F (175°C). Transfer the lobster mac and cheese to a greased 2-quart baking dish.
If desired, sprinkle breadcrumbs evenly over the top for a crunchy topping. Bake in the preheated oven for 15-20 minutes, or until bubbly and golden brown on top.
Once baked, let it sit for a few minutes before serving. Garnish with chopped parsley for a fresh touch.