Slice the onions and mince the garlic.  Melt the butter on medium heat in a dutch oven or large pan.  Add the garlic and cook for a minute.  Add the onion slices.  Stir to mix the butter with onions.   

Reduce heat to medium low.  Cover and cook until the onions are tender about 20-30 minutes.  Stir occasionally.

Add broth and bouillon to onions.  Simmer on medium for about 30 minutes.

Just before serving broil the french bread slices until lightly toasted.  Flip slices over and cover uncooked side with cheese.  Broil until cheese is melted and starting to brown.

To serve fill a bowl with a ladle of soup and top with a toasted bread slice.