I have always been torn between two of the world’s most perfect comfort soups: the deep, savory, cheese-laden glory of French Onion, and the earthy, velvety richness of Cream of Mushroom. One day, I decided to stop choosing and combine them. The result is this Creamy French Onion and Mushroom Soup a recipe that takes the best elements of both classics and creates something truly spectacular.
You are going to be captivated by this soup. It starts with onions, patiently caramelized until they are jammy and sweet, then builds layers of flavor with earthy mushrooms, rich beef broth, and a touch of tangy vinegar. A final swirl of heavy cream gives it a luxurious, silky body that’s all capped off with the essential bubbly, golden-brown Gruyère toast. It’s an elegant, deeply satisfying soup that feels both familiar and brand new.
The Ingredients for This Ultimate Comfort Soup
- 4 tablespoons butter
- 1 tablespoon olive oil
- 4 medium yellow onions, thinly sliced
- 8 ounces cremini mushrooms, sliced
- 3 cloves garlic, minced
- 2 tablespoons all-purpose flour
- 6 cups beef broth
- 2 tablespoons fresh thyme, chopped
- 1 tablespoon red wine vinegar
- 1 tablespoon Worcestershire sauce
- ¼ cup heavy cream
- 1 teaspoon white sugar
- salt and ground black pepper to taste
Topping:
- 8 (1-inch thick) slices French baguette
- 1 cup shredded Gruyère cheese
How to Create Your French Onion and Mushroom Soup
Step 1: Caramelize the Onions
This is the most important step for developing deep flavor. In a large Dutch oven or heavy-bottomed pot, melt the butter and olive oil over medium heat. Add the thinly sliced onions and the sugar. Cook, stirring occasionally, for 30-40 minutes, until the onions are deeply golden brown, soft, and sweet. Be patient; this slow caramelization is key.
Step 2: Sauté the Mushrooms and Build the Base
Add the sliced cremini mushrooms to the pot with the caramelized onions and cook until they have released their liquid and started to brown, about 8-10 minutes. Stir in the minced garlic and cook for another minute until fragrant. Sprinkle the flour over the onion and mushroom mixture and stir constantly for one minute to cook out the raw flour taste.
Step 3: Simmer the Soup
Slowly pour in the red wine vinegar to deglaze the pot, scraping up any browned bits from the bottom. Whisk in the beef broth until smooth, then stir in the fresh thyme and Worcestershire sauce. Bring the soup to a simmer, then reduce the heat to low, cover, and let it cook for at least 20 minutes to allow the flavors to meld.
Step 4: Finish with Cream and Prepare Toasts
Remove the soup from the heat and stir in the heavy cream. Season with salt and pepper to taste. While the soup is resting, turn your oven’s broiler on high. Arrange the baguette slices on a baking sheet. Ladle the hot soup into oven-safe bowls, place a baguette slice on top of each, and cover generously with the shredded Gruyère cheese. Place the bowls under the broiler for 2-3 minutes, or until the cheese is melted, bubbly, and golden brown. Serve immediately and with caution, as the bowls will be very hot.
My Best Tips for This Creamy Soup
My Secret for Truly Caramelized Onions
The secret to perfect French onion soup is patience. Don’t try to rush the caramelization process by turning up the heat. Cooking the onions low and slow allows their natural sugars to release and sweeten, creating a deep, complex flavor base that is the soul of the soup. The small pinch of sugar helps kick-start this process.
The Power of the Deglaze
When you’re cooking the onions and mushrooms, they’ll leave behind delicious browned bits stuck to the bottom of the pot. This is called the “fond,” and it’s packed with flavor. When you add the red wine vinegar, use your spoon to scrape these bits up. This deglazing step releases all that concentrated flavor back into your soup broth.
Don’t Crowd the Mushrooms
For the best earthy, savory flavor, you want to brown your mushrooms, not steam them. After you add them to the hot pan, spread them out as much as possible and let them cook for a few minutes without stirring. This gives them a chance to get a good sear and develop a deep, caramelized flavor before they release all their water.
Delicious Variations to Try
This soup is a wonderful canvas for your own touches. For a more traditional French onion flavor, you can substitute the red wine vinegar with a dry white wine like Sauvignon Blanc or Pinot Grigio. Feel free to experiment with the cheeses; a mix of Swiss, provolone, or even a sharp white cheddar would be delicious. For an even richer, more umami-packed broth, try using a combination of beef and mushroom broth.
FAQs
Can I make this soup ahead of time?
Yes, this soup is perfect for making ahead! You can prepare the soup base completely and store it in the refrigerator for up to 3 days. The flavors will actually deepen and improve overnight. When you’re ready to serve, simply reheat the soup on the stove and prepare the cheesy baguette toasts fresh under the broiler.
Can I make this soup vegetarian?
Absolutely. To make a vegetarian version, simply substitute the beef broth with a high-quality, flavorful vegetable broth. A mushroom broth would be an especially good choice to enhance the earthy flavors of the dish.
What if I don’t have oven-safe bowls?
No problem! You can still enjoy the best part of the soup. Simply place the toasted baguette slices on a baking sheet, top them with the Gruyère cheese, and broil until melted and bubbly. Then, you can float these cheesy “croutons” on top of the soup when you serve it in regular bowls.
Creamy French Onion and Mushroom Soup
- Total Time: 90
- Yield: 6-8 servings 1x
Description
This Creamy French Onion and Mushroom Soup is the ultimate comfort food, combining two classic soups into one spectacular dish. It features patiently caramelized sweet onions and earthy mushrooms in a rich beef broth, finished with a swirl of cream for a luxurious, silky body. Topped with a bubbly, golden-brown Gruyère toast, this elegant soup is deeply satisfying and feels both familiar and brand new.
Ingredients
4 tablespoons butter
1 tablespoon olive oil
4 medium yellow onions, thinly sliced
8 ounces cremini mushrooms, sliced
3 cloves garlic, minced
2 tablespoons all-purpose flour
6 cups beef broth
2 tablespoons fresh thyme, chopped
1 tablespoon red wine vinegar
1 tablespoon Worcestershire sauce
¼ cup heavy cream
1 teaspoon white sugar
salt and ground black pepper to taste
Topping:
8 (1-inch thick) slices French baguette
1 cup shredded Gruyère cheese
Instructions
Caramelize the Onions:
In a large Dutch oven, melt the butter and olive oil over medium heat. Add the sliced onions and sugar. Cook, stirring occasionally, for 30-40 minutes, until the onions are deeply golden brown, soft, and sweet.
Sauté the Mushrooms and Build the Base:
Add the mushrooms to the pot and cook for 8-10 minutes until browned. Stir in the garlic and cook for one more minute. Sprinkle the flour over the mixture and stir for one minute.
Simmer the Soup:
Deglaze the pot with red wine vinegar, scraping up any browned bits. Whisk in the beef broth, then stir in the thyme and Worcestershire sauce. Bring to a simmer, then reduce heat, cover, and cook for at least 20 minutes.
Finish with Cream and Prepare Toasts:
Remove the soup from the heat and stir in the heavy cream. Season with salt and pepper. To serve, turn the oven’s broiler on high. Ladle soup into oven-safe bowls, top each with a baguette slice, and cover with Gruyère cheese. Broil for 2-3 minutes until the cheese is melted and bubbly. Serve immediately.
Notes
Vegetarian Version:
To make this soup vegetarian, simply substitute the beef broth with a high-quality, flavorful vegetable or mushroom broth.
No Oven-Safe Bowls?
If you don’t have oven-safe bowls, you can prepare the cheesy toasts separately. Place the baguette slices on a baking sheet, top with cheese, and broil until melted. Float these “croutons” on top of the soup when serving.
Make-Ahead Friendly:
The soup base can be made up to 3 days in advance and stored in the refrigerator. The flavors will deepen overnight. Reheat the soup on the stove and prepare the cheesy toasts just before serving.
- Prep Time: 15
- Cook Time: 75
- Category: Soup, Main Course
- Method: Sautéing, Simmering
- Cuisine: French-American
Nutrition
- Serving Size: 1 serving
- Calories: 450
- Sugar: 12g
- Sodium: 950mg
- Fat: 30g
- Saturated Fat: 16g
- Unsaturated Fat: 12g
- Carbohydrates: 28g
- Fiber: 4g
- Protein: 15g
- Cholesterol: 80mg
Keywords: french onion soup, mushroom soup, creamy soup, comfort food, gruyere cheese, caramelized onions
