Bring a large pot of water to a boil. Cook the macaroni until still very firm; the macaroni should be too firm to eat right out of the pot. Drain and set aside.
Preheat the oven to 350 degrees F. Butter a 9-by-13-inch pan generously.
Melt 2 tablespoons butter in a large skillet over medium-high heat. When it just starts to brown, throw in the lobster and stir and cook for 1 minute. Set the lobster aside.
Add the remaining 4 tablespoons butter to the same skillet. Sprinkle in the flour, whisking to combine. Let the roux cook for a minute or so, whisking constantly. Pour in the milk, whisking constantly, then cook the white sauce until thick and bubbly, 3 to 5 minutes. Next, add the half-and-half, 1 teaspoon of salt and plenty of black pepper, and stir to combine. Add the Parmesan (holding back some for the topping), Cheddar, fontina and goat cheese and stir them around to melt. Stir in the lobster and macaroni.
Pour the mac and cheese into the prepared pan and top with the reserved Parmesan. Bake until bubbly and a slight crust forms on top, 20 to 25 minutes.