Follow the steps in order for the best result.
Begin by preparing the cheese sauce. In a heavy-bottomed pot, melt the butter over medium heat. Sauté the chopped garlic and minced shallot in the melted butter for about 1 minute, until fragrant.
Incorporate the flour into the butter mixture, stirring continuously with a wooden spoon to form a roux.
Gradually whisk in the milk, about 1 cup at a time, ensuring that any lumps are thoroughly worked out.
Add the bay leaf and nutmeg, then reduce the heat to low and let the sauce simmer gently for 5 minutes.
Stir in the grated cheddar and parmigiano-reggiano cheeses. Continue to cook and stir until the cheese is completely melted and fully incorporated into the sauce. Season with salt and pepper to your liking.
For the crumb topping, combine the panko breadcrumbs (or regular breadcrumbs), smoked bacon, and grated parmigiano-reggiano cheese in a food processor. Pulse on low speed until the bacon is evenly incorporated into the breadcrumbs.
Cook the elbow macaroni in a large pot of boiling water (without added salt) until al dente. Drain the noodles thoroughly.
To assemble the dish, add the cooked macaroni to the cheese sauce. Mix in the lobster pieces and cooked bacon.
Transfer the mixture to a casserole dish and spread it evenly. Sprinkle the crumb topping generously over the top.
Bake in a preheated oven at 350°F (175°C) until the crumb topping is golden brown and the casserole is bubbly. Remove from the oven and let it cool slightly before serving.