Preheat oven to 350 degrees F (175 degrees C).
Bring a large pot of salted water to a boil, then add the macaroni and cook according to package instructions. Drain and set aside.
In a large pot or Dutch oven, melt the butter over medium heat. Stir in the flour and salt, then cook for 1 minute.
Pour in the milk and cream, whisking continually until the mixture comes to a boil.
Reduce the heat to low and add the Parmesan cheese, Cheddar cheese, Gruyere cheese, and black pepper. Stir until the cheeses are melted and the sauce is smooth.
Add the cooked macaroni and lobster meat to the sauce and stir to combine.
Transfer the mixture to a greased 9x13 inch baking dish and bake for 20-25 minutes, or until bubbly and golden brown on top. Serve immediately. Enjoy!