Baked french onion soup

3 tablespoons vegetable oil
6 medium white onions, sliced
8 cups beef broth (Swanson is best)
1 cup water
2 1/2 teaspoons salt
1/2 teaspoon garlic powder
1/4 teaspoon ground black pepper
5 plain hamburger buns
10 slices provolone cheese
10 teaspoons shredded parmesan cheese

1. Add 3 tablespoons oil to a large soup pot or saucepan over medium/high heat. Add the sliced onions and sautй for 20 minutes until the onions begin to soften and start to become translucent. You don't want them to brown.
2. Add the beef broth, water, salt, garlic powder and black pepper to the pan and bring mixture to a boil. When soup begins to boil, reduce heat and simmer for 45 minutes.
3. To make the croutons cut off the top half of each top of the hamburger bun so that the bread is the same thickness as the bottom half of each bun. Throw the tops away. Now you should have 10 round pieces of bread -- 5 bottom buns, and 5 top buns with the tops cut off. Preheat oven to 325 degrees. Place the bread in the the oven directly on the rack and bake for 15 to 20 minutes or until each piece is golden brown and crispy. Set these croutons aside until you need them.
4. When the soup is done, spoon about 1 cup into an oven-safe bowl. Float a crouton on top of the soup, then place a slice of provolone cheese on top of the crouton. Sprinkle 1/2 teaspoon of shredded parmesan cheese over the provolone.
5. Place the bowl into your oven set to high broil. Broil the soup for 5 to 6 minutes or until the cheese is melted and starting to brown (you may need to broil longer if you are making more than one bowl at a time). Sprinkle an additional 1/2 teaspoon of shredded parmesan cheese over the top of the soup and serve. Repeat process to prepare remaining servings.