Vegetable oil cooking spray
5 medium sweet white onions, such as Vidalia
2 teaspoons extra-virgin olive oil
Salt and freshly ground black pepper
1 cup low sodium beef broth
2 teaspoons low sodium soy sauce
1 cup finely shredded Gruyère cheese (4 ounces)
2 teaspoons finely chopped fresh sage
Preheat the over to 400 degrees. Spray a large, shallow baking dish with cooking spray. The baking dish should be large enough to hold 10 onion halves.
Cut about ¼ inch off the top and bottom of the onions so that the halves will be able to sit on a plate. Cut the onions in half at the equator and then peel them. Arrange the onion halves, cut sides up, in the baking dish.
Brush the exposed tops of the onions with olive oil and sprinkle with salt and pepper. Bake for about 35 minutes.
In a glass measuring cup, mix together the beef broth and soy sauce and pour this over the onions. Continue baking the onions for about 1 hour longer, basting occasionally. If the liquid evaporates, add a little water.
Sprinkle the cheese and sage evenly over the onion halves. Bake for 5 to 7 minutes more or until the cheese melts.