Caramelized onion soup in mushroom broth is a delicious, vegetarian soup. It is virtually impossible to determine that the broth is of purely vegan base.  The caramelized onions can be used freshly made or from your freezer and so is the mushroom broth. To finish the soup, we place a piece of toasted ciabatta bread on top. On top of this we place grated gruyere cheese and ladle a little of the hot broth on top of this. It will cause the cheese to melt, and no separate oven treatment is necessary.  Serve this soup as a whole meal soup for simple lunches or make it an exquisite starter for any multi course dinner.

the art of making caramelized onion soup in mushroom broth

This soup comes together very easily. Assuming caramelized onions are ready and the mushroom broth made. If so, bringing it all together is a 5-minute job.

Obviously, you can opt to use a different broth. Either coming from a can, a purely vegetable broth or even from a broth cube (the latter I do not recommend). But the mushroom broth provides the deepest, umami flavor.

Special equipment

no special equipment is needed

Caramelized onion soup in Mushroom broth ©️ Nel Brouwer-van den Bergh

Caramelized Onion Soup in Mushroom Broth

Prep Time 1 minute
Cook Time 4 minutes
Total Time 5 minutes
Course Appetizer, Dinner, Lunch
Cuisine French
Servings 4


ingredients for the soup

  • 2 cups caramelized onions
  • 6 cups mushroom broth
  • 4 pieces of ciabatta bread (or other bread)
  • 2 oz gruyere cheese to grate


How to bring it together

  • mix the broth and the opnions in a pan
  • heat the pan
  • ladle the soup in bowls
  • Cover the bowls with a piece of (toasted) ciabatta
  • grate the gruyere cheese on top
  • ladle a small amount of hot broth on the cheese to melt it
  • serve hot


Method: simmering
Food allergy & intolerance information: none


If you like to completely cover the bowl with a cheese crust, then follow these instructions.  First, fill the bowl to about 1/2 inch from the rim. Then place the crusty ciabatta bread on top and generously grate the gruyere cheese on top of it. Place in the oven or grill long enough to have the cheese melted and turn some color.

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