1 whole; small brown onion, cut into thin slices
1 cup, chopped mushrooms
1 tablespoon; olive oil
Mozzarella cheese (Gruyère is ideal, but not easy to find at the average grocery store)
1 package; french onion soup mix
4 cups; water
In a large deep sauce pan, sauté onions and mushrooms in olive oil until onions are translucent, about 10 minutes. Mix in packet of soup mix and water. Bring to a boil, and then reduce heat and allow to simmer for 10 more minutes. Once soup has thickened, ladle into individual ramekins (must be oven-safe dish).
Top with 3 or 4 croutons, and then cover croutons with a slice of cheese. Place into oven or toaster oven and broil until cheese bubbles and browns. Serve immediately.