Preheat the oven to 350 degrees F. Wash the potatoes; dry and then prick them several times with a fork. Bake until tender, about 50-60 minutes. Meanwhile, set a large, non-stick skillet over medium heat. Add the beef, onion and garlic and cook, stirring to break up the meat, until the beef is cooked through, about 5 minutes.
Drain away the excess fat, and then add the remaining ingredients, except the cheese and green onions. Gently simmer for 15 minutes; the mixture should be loose, with just enough sauce to bind the meat (if it gets too thick, add a bit of water). When the potatoes are cooked, make a slit in the middle of them and squeeze the potatoes open to expose the flesh. Top with a generous amount of the sloppy Joe mixture.
Sprinkle with the cheese and green onions and serve.