Mushroom & Caramelized Onion Soup
This Mushroom & Caramelized Onion Soup is the ultimate umami bomb. It’s built around the rich flavors of sauteed mushrooms and caramelized onions. We’ve also added marsala wine, vegetable broth, fresh thyme, and a parmesan cheese rind to take it over the top.
Better than the Canned Version
If you’re an American of a certain age, chances are you grew up eating something made with canned cream of mushroom soup. Full disclosure: we never liked that soup as kids. While we don’t dislike canned mushroom soup now, we strongly prefer this homemade version.
The mushroom flavor in this soup is richer than the canned option. The caramelized onions also add a sweetness that goes so well with the umami flavor of the fungi.
We love making chicken marsala or mushroom marsala pasta, so it seemed natural to add marsala wine to this mushroom soup as well. And let us tell you, it is INSANELY good in this soup! It adds richness and a nutty, sweet flavor that makes this dish taste and feel super special. And fancy. This soup feels fancy.
The soup is rounded out with a touch of heavy cream to make it extra decadent, and topped with parmesan crisps (homemade or store bought) for some crunchy texture.
Ingredients in this Mushroom & Caramelized Onion Soup
This vegetarian soup has simple ingredients that deliver on flavor:
- Cremini mushrooms – these are also called “baby bella” mushrooms.
- Red onions – we like the flavor and umami richness of red onions, but you can use any onion you like.
- Dry marsala wine – sweet marsala will work okay too. It just may make the soup a touch sweeter.
- Vegetable broth – our favorite vegetable broth is made by Better Than Bouillon.
- Butter + flour – this soup uses a roux (melted butter cooked with flour) to give it thickness.
- Fresh thyme – mushrooms love thyme, and it gives this soup a nice earthiness.
- Parmesan rind – if you haven’t been putting parmesan rinds in your soup, you need to. It gives soups a delicious umami flavor.
- Heavy cream – you could also use half and half, but the soup will be thinner and not quite as rich.
- Optional toppings – we like to top our soup with extra sauteed mushrooms and onions, (you can make extra or reserve some from the soup before blending), fresh thyme, and parmesan crisps.
How to Make this Soup
To make this soup, first melt 1 tablespoon of butter in a large pot or Dutch oven. Add the mushrooms and cook for 8 to 10 minutes or until they have browned. Season with salt, then remove them from the pot and set aside.
Add 2 more tablespoons of butter and all of the onions to the pot. Season them with salt and pepper and cook them for about 20 to 25 minutes, adding up to a half cup of water (¼ cup at a time) if they’re looking dry.
Add the mushrooms back to the pot with the onions and make a well in the center. If you want to top your soup with a few mushrooms and onions at the end, remove a small amount now because you’ll be blending the rest.
Melt 3 tablespoons of butter in the well, then add the flour to the melted butter and mix them together to make a roux. Toss the flour mixture with the mushrooms and onions until they’re coated and cook for a minute to cook off the flour taste.
Stir in the marsala wine to deglaze the pot, then add the broth and bring the mixture to a boil.
Add the thyme and parmesan rind, then cover the pot with a lid.
Cook the soup on low heat for 15 to 20 minutes, then remove the lid and turn off the heat. Remove the parmesan rind and thyme sprigs.
Using an immersion blender, blend the soup while adding in the cream. Top the soup with desired toppings (we like parmesan crisps or grated parmesan) and serve with crusty bread.
Mushroom & Caramelized Onion Soup
Ingredients
Soup
- 16 oz cremini mushrooms, sliced
- 2 red onions, quartered & sliced
- ½ cup marsala wine
- 6 cups vegetable broth
- 6 tbsp butter
- 3 tbsp all-purpose flour, or can use same amount of 1:1 gluten-free flour
- 8 sprigs fresh thyme
- 3 inches of a parmesan rind
- 1 cup heavy cream
- ½ cup water, if needed
- Salt & pepper to taste
Optional Toppings
- Parmesan crisps, store bought or homemade
- Fresh thyme
- Extra sauteed mushrooms & onions
Instructions
- In a large pot or Dutch oven, melt 1 tbsp butter and add the mushrooms. Cook for 8-10 minutes or until browned. Season with salt, then remove from the pot and set aside.
- Add 2 tbsp butter and all of the onions to the pot. Season with salt and pepper and cook for about 20-25 minutes, adding up to ½ cup of water (¼ cup at a time) if they’re looking dry.
- Add the mushrooms back to the pot with the onions and make a well in the center. If you want to top your soup with a few mushrooms and onions, remove a small amount now.
- Melt 3 tbsp butter in the well, then add the flour to the melted butter and mix to make a roux. Toss the flour mixture with the mushrooms and onions until they’re coated and cook for a minute to cook off the flour taste.
- Stir in the marsala wine to deglaze the pot, then add the broth and bring the mixture to a boil.
- Add thyme, parmesan rind, and cover the pot.
- Cook on low heat for 15 to 20 minutes, then remove the cover and turn off the heat.
- Remove the parmesan rind and thyme sprigs.
- Using an immersion blender, blend the soup while adding in the cream.
- Top the soup with desired toppings and serve with crusty bread.
