Cook pasta according to directions on package. Drain and set aside.
Warm milk in the microwave or in a small saucepan over medium heat. Do not allow to boil. Set aside.
Melt 6 Tbsp butter over medium heat. Stir in flour and cook for 2 minutes, stirring constantly with a whisk. Whisk in warm milk until smooth. Remove from heat and stir in shredded cheese until smooth. Stir in cooked pasta and lobster. Transfer mixture to a large casserole dish, or 2 smaller baking dishes.
Melt the additional 2 Tbsp butter and stir into breadcrumbs. Sprinkle breadcrumbs over macaroni. Bake for 30-35 minutes until breadcrumbs are golden brown.