Combine ground beef, 3 tablespoons worcestershire sauce, salt and pepper. Form into 4 patties, cook in large skillet until desired doneness. Remove from skillet to plate, cover with foil to keep warm. In same skillet add olive oil and butter, add mushrooms, onions and carrots, cook on medium heat until vegetables are tender, add garlic, cook about 1 minute,(add a couple of tablespoons of olive oil if needed to make gravy) sprinkle flour over vegetables, stir, add 3 tablespoons worcestershire sauce and enough beef stock to make gravy to desired consistency, add salt and pepper to taste. Add hamburgers to gravy and simmer about 5 minutes.