Preheat oven to 375 degrees F.
Heat milk in a small saucepan, but don’t boil it. It should be hot when you add it to the sauce mixture.
In a separate sauce pot, over low heat, melt 8 tbsp. Butter. Add the flour, and cook over low heat for two minutes, stirring with a whisk. Still whisking, add the hot milk and cook for a couple minutes more, until thickened and smooth. Add the shredded cheeses, tbsp. of salt, the pepper and nutmeg. Stir, taste, and add more seasoning to taste. Set sauce aside but keep it warm.
In a large pot of salted, boiling water, add a splash of oil, and then cook pasta according to directions for al dente. Drain well. Add pasta back to large cooking pot, and stir in lobster and most of the cheese sauce. I keep a bit, as sometimes the pasta will get dry when you bake it, so I like to reserve a little to add as I’m eating.
Portion the pasta into individual gratin dishes or larger casserole.
Melt remaining 3-4 tbsp. butter and combine them with croutons crumbs and Panko crumbs. Sprinkle on top, and bake 30 minutes or until sauce is bubbly and crumbs are golden. Serve immediately for moist pasta.