@Avram in MD
French Onion Soup is NOT designed for dairy, it is a beef based soup full of onions with a crouton or piece if crusty bread across the top that the non-kosher world finishes with Gruyere cheese melted on top.
Imitation kosher versions may have a pareve soup base instead of beef and cheese melted on top,
or beef based soup with imitation pareve cheese on top.
Personally I prefer just the beef based soup with all the onions and crusty bread to dip in the bowl. Not a fan of cheese