Step 1

Melt butter in large skillet on medium heat. Add onions; cook 15 min. or until golden brown, stirring frequently. Add beef broth, water and bay leaf; stir. Bring to boil; cover. Simmer on medium-low heat 15 min. Remove and discard bay leaf.

Step 2

Heat broiler. Ladle soup evenly into 6 ovenproof bowls; top each bowl of soup with 2 toast slices. Sprinkle evenly with cheeses.

Step 3

Broil 5 to 10 min. or until cheese is golden brown.