• 3 1/2 tablespoons butter
• 2 tablespoons olive oil
• 2 onions, peeled and finely diced
• 1 carrot, peeled and finely diced
• 1 pound ground lamb or ground beef, lean
• 1 teaspoon worcestershire sauce
• 1 tablespoon tomato purée
• 3 1/2 ounces cheddar and mozzarella cheese mix