Caramelized onions are heaped onto stale rafts of bread, which then simmer in an herb broth, making an extremely rustic dish. You can use this technique with other vegetables such as braised cabbage or roasted winter squash. But regardless of the vegetable, use strong, very stale (that is, hard) bread such as sourdough or rye.
Heat oil in a large Dutch oven coated with cooking spray over medium-high heat. Add onion; cook 20 minutes or until deep golden brown, stirring frequently.
Preheat oven to 450°.
Place bread slices in a single layer in an 11 x 7-inch baking dish. Spoon the caramelized onions over bread; sprinkle with cheeses and sage. Bring Herb Broth to a boil in a small saucepan. Pour broth around sides of dish to avoid disturbing bread layers. Bake at 450° for 22 minutes or until cheese melts. Sprinkle with parsley and pepper.