Cut lobster in half. Remove organs and discard; remove meat. Cut into large chunks and set aside. Bring a large pot of water to a boil; drop in lobster shells to clean, about 5 minutes. Set aside.

Heat butter in a skillet over medium heat until just beginning to brown, 3 to 4 minutes. Add lobster meat, onion, and garlic; cook and stir until onions and garlic are softened, and meat is cooked through but not colored, about 5 minutes.

Stir in whiskey and set on fire carefully with a lighter. Add cream once alcohol has burned off, or when flames are out. Cook until cream is heated through, 3 to 4 minutes more. Return meat and cream sauce to cleaned shell halves to serve.