Our family loves Patty Melts, but the ones in restaurants can run up over 1000 calories. I'm always looking for a lighter side in recipes and I found it in this one - with about 350 calories per sandwich. Pair it with some oven baked fries or some oven fried onion rings and it won't totally demolish your calorie intake and it still packs great flavor.
Heat oil in skillet. Mix meat, worcestershire, water and seasonings. Mix well with hands. Make patties (they will be a bit "runny" because of the water, but that's ok.) Put patties in skillet, add diced onion and scatter around the burgers. Stir onions from time to time so as not to burn. Cook burgers until desired doneness - 3-4 minutes per side is good; flip burgers and continue to cook. Add cheese to top of burgers. When onions are tender, add to top of cheese. Remove and place on rye bread. Brush sides of rye bread with butter and add back to the skillet to toast each side of bread.