3
Heat milk in a small saucepan but don't let it boil. In a large pot, melt 6 Tbsp butter and add flour. Cook over low heat for 2 minutes, stirring with a whisk. Still whisking, add hot milk and cook another minute or two, until thick yet smooth. Remove from heat and add Gruyère, Cheddar, salt, pepper, and nutmeg. Add cooked macaroni and lobster; stir well. Place in 6 to 8 individual gratin dishes.
4
Melt remaining 2 Tbsp butter, combine with fresh bread crumbs, and sprinkle on top of each dish. Bake for 30 to 35 minutes, or until sauce is bubbly and the top is brown.