Preheat oven to 350 degrees F.

Cook the pasta in well-salted water (for timing, use package directions but make sure the noodles are al dente). Drain and set aside.

While pasta is cooking, make the cheese sauce. Melt 4 tablespoons of butter in a large, heavy saucepan over medium heat. Add the flour and the mustard powder and whisk to combine. Cook over medium-low heat for about 2-3 minutes, whisking constantly. Slowly add the milk while whisking and cook over medium heat for about 5 minutes or until the sauce thickens (it won’t thicken fully until it’s almost at a boil), whisking often. Add the hot sauce. Turn heat to low and cook for about 10 minutes, stirring occasionally.

Next, prepare the breadcrumb topping. Melt 2 tablespoons of butter in a small skillet over medium high heat. When the butter stops foaming add the garlic and cook for 30 seconds or until fragrant. Add the breadcrumbs and toss with the butter, Raise the heat to med-high and toast for a few minutes until the bread crumbs become golden. Stir in the lemon zest and season with kosher salt and fresh pepper. Remove from heat to cool.

Once the sauce has thickened, remove from heat and slowly add the cheeses a handful at a time until it’s all incorporated, stirring with each addition. If the cheese isn't melting, turn the burner on low and heat just until the cheese melts and becomes smooth with the sauce.

Add the drained pasta to the sauce and stir to combine, making sure the sauce evenly coats the pasta. It will look like a lot of sauce but the pasta will soak it up while it bakes. Gently fold in the lobster meat.

Spoon the mixture into a buttered 9 X 13 baking dish or 6 - 8 small gratin dishes. Sprinkle the bread crumb mixture on top of the pasta and bake for about 20 - 25 minutes, until the pasta is bubbly and lightly browned on top.