For the Topping: Melt oil and butter over medium heat in a large sauté pan, preferably nonstick. Add breadcrumbs, toss to coat, and cook for a minute or two, just until crumbs begin to take on color and smell fragrant (like garlic toast). Remove from heat and stir in Parmigiano Reggiano and salt; set aside.

For the Pasta, Lobster & Sauce: Position rack in middle of oven. Preheat oven to 400°F/200°C. Butter the inside of a 13 x 9 inch (33 cm x 23 cm) ovenproof dish with the 1 tablespoon of butter; set aside.

Bring a large stockpot of salted water to a rolling boil. Add lobster tails and whole lobster (if using), cover, and cook lobster until done, about 3 to 5 minutes for tails and about 10 minutes for whole lobster. The shells should be bright red. The tail shells should be tightly curled around and the tail flesh should be creamy white, with no translucence. You can also tug at one of the antennae; it should separate easily from the head.

Remove lobster(s) from water, reserving water. Let lobsters cool, crack open the lobster shells, drain away and discard any liquid and roughly chop the flesh. (You can save one whole claw for decorative purposes like we did).

Bring the lobster water back to a boil and cook pasta until it is very firm, even more so than “al dente”, and still has a slight firmness; do not overcook as pasta will cook further in oven. Drain; run under cold water to stop cooking.

Melt 1/2 cup (113 g) butter in large pot over medium heat then whisk in flour until combined to make a roux. Cook over medium heat, whisking almost constantly, for about 2 minutes or just until roux is very light brown. Slowly add milk, whisking all the while. Continue to cook over medium heat, bringing back to a low boil, whisking all the while, for about 3 minutes or until sauce is thick and creamy. You should be able to see whisk marks for a moment before they dissolve back into the sauce. Remove from heat and slowly add grated cheddar, Gruyere and Parmigiano Reggiano, whisking them in as you go. The residual heat should melt the cheeses. Whisk gently until cheeses are melted, incorporated and the sauce is thick and smooth. Season with salt and pepper, going lightly on the salt as the pasta and lobster will be adding salinity. Stir in pasta and cooked lobster meat. Scrape into prepared pan, then sprinkle toasted breadcrumbs evenly over top, or along the edges. (Your Lobster Mac n’ Cheese may be covered with aluminum foil at this point and held at room temperature for 2 hours before baking, refrigerated overnight or frozen for up to 1 month. Bring to room temperature before baking).

Bake for about 25 to 35 minutes or until edges are bubbling and topping is light golden brown. Lobster Mac n’ Cheese is ready to eat. Leftovers may be covered with plastic wrap or placed in airtight containers and refrigerated for up to 3 days. Reheat in microwave or in a 300°F/150°C oven covered with foil to prevent it from drying out.