To make homemade ham stock, add ham bone to ham grease from cooked ham (optional), and simmer on medium low with 4 -5 quarts of water until stock is rich and flavorful. 2-4 hours.
Saute sliced onions with garlic and butter slowly on medium / low heat, stirring constantly. Be sure that the onions do not burn!
Add sautéed onions to a large dutch oven or pot with ham stock and heat on medium until stock is hot. Add salt and pepper.
Turn oven to broil and bring tray to top, leaving enough room for soup crock.
Fill soup crocks with onions and broth, add fresh sliced bread, top with cheese. Put crocks on baking sheet (to catch any dripped cheese) and broil for 1-2 minutes until the cheese is melted and slightly brown.
Yields about 4 quarts of broth with onions. Plenty for leftovers or to be frozen for later use!