Slice onion with an apple slicer to make wedges and open up the onion. Season onion with garlic powder, onion salt and pepper. place onion on top of a foil sheet. Add 1/4 cup of broth. Wrap foil tightly around onion. Place in baking dish and bake at 350 for 1 hour. Remove from oven, unwrap onion and place in a bowl . Pour remaining beef broth (and water, if needed) over onion and serve.