Here's another recipe of it to try. This was in one of the first Crockpot recipe books, 40 years ago and this is the recipe I have used, that long. Am waiting for it to cool to fall here in FL so I can fix it. It'll beat any recipe, homecooked or in a restaurant.
CROCKPOT FRENCH ONION SOUP
3 large onions, thinly sliced
1/2 cup butter or margarine
6 beef bouillon cubes
4 cups hot water
1 Tbs. Worcestershire sauce
Sliced French bread (or you can use croutons)
Grated Parmesan cheese
In large skillet, cook onions in butter until lightly browned. In the crockpot, combine browned onions in the butter, with the bouillon cubes, water, Worcestershire sauce and salt. Cover and cook on low four to six hours. Makes four servings. To serve, top each bowl of soup with a toasted slice of French bread then sprinkle with Parmesan cheese.
My tips are, I always double the recipe, because it's excellent reheated and I never add the salt, the bouillon cubes tend to be salty. This soup smells so good cooking all day. Hope you enjoy.