• In a large heavy bottom pot, melt butter over medium heat.  Add onions, salt, and bay leaves.  Cover pot, and cook over medium-high for 4-5 minutes, until they begin to look translucent and start releasing water.
• Remove lid, and cook onions over low (or medium-low) until they caramelize.  This will take 2-5 hours, depending on the size of your pot and the temperature used.  The onions can be left alone and checked on about once an hour, except at the beginning and end of the caramelizing process. 

  Tip-- this can be done ahead of time, and the onions frozen until you're ready to use them.
• When onions have reduced and are an amber color, you're ready.  Increase the heat to medium-high and add the wine.  Allow the wine to boil down for 3-4 minutes.
• Add 5 cups of hot water and the rosemary, and bring to a boil.  Then, reduce to a simmer. 

  Taste soup. If you prefer a milder flavor, add another cup of hot water.  If desired, add another splash of wine.  If the soup is too bland, add extra salt. Remove the bay leaves.
• Turn on oven broiler.
  

If using oven-safe bowls:

• Ladle soup into bowls, then set bread into soup.  Pile desired amount of cheese over bread.  Set bowls onto a baking tray, and set under broiler 1-2 minutes until cheese has melted and is golden. 
  Garnish soup with fresh herbs (optional), and serve immediately.
  

If NOT using oven-safe bowls:

• Lay bread cubes on baking sheet and top with cheese.  Set in oven under broiler for 1-2 minutes, until cheese has melted and is golden. 

  Ladle soup into bowls, and set cheese bread on soup.  Garnish soup with fresh herbs (optional), and serve immediately.