5 tablespoons extra virgin olive oil
8 large Maui or Vidalia onions (6 to 7 pounds), peeled and thinly sliced
1 tablespoon sugar
8 cups chicken broth, homemade or low sodium canned
3 cups dry white wine
1 cinnamon stick
6 slices several-day-old crusty Italian bread broken into pieces (2-3 cups)
Salt to taste
1 cup freshly grated Parmigiano Reggiano cheese
Heat the oil in a large pot over medium heat. Add the onion and cook over medium heat stirring constantly, until pale yellow and soft, about 15 minutes. Sprinkle with the sugar and mix. Add the broth, the wine and the cinnamon stick and bring to a boil.
Cover the pot and simmer the soup over medium-low heat stirring from time to time, for about 1 hour. Add the bread and simmer uncovered 20-30 minutes longer.
Turn the heat off and discard the cinnamon stick. With a wire whisk beat the soup lightly until the bread is completely broken up and the soup has a thick consistency. Season with salt. Serve hot or at room temperature with a sprinkling of Parmigiano.