Name: French Onion Soup with Mushrooms, Extra Herbs & Cheesy Croissant Topping
Prep time: 15 min
Cook time: 45 min
Total time: 1 h
Cuisine: French
Ingredients: 4 large yellow onions, thinly sliced; 8 oz mushrooms (cremini or baby bella), sliced; 2 tbsp olive oil; 2 tbsp butter; 3 cloves garlic, minced; 2 tbsp all-purpose flour; 6 cups beef broth or vegetable broth; 1/2 cup dry white wine (optional); 1 tsp fresh thyme, chopped; 1 tsp fresh rosemary, chopped; 1 bay leaf; Salt, to taste; Black pepper, to taste; 2 croissants, sliced into rounds or halves; 1 1/2 cups shredded gruyère or swiss cheese

Jump to Recipe·Leave a Review

This French onion soup with mushrooms, extra herbs, and a cheesy croissant topping is one of my favorite cozy bowls when I want something rich, savory, and deeply comforting. I love how the caramelized onions and mushrooms create layers of flavor, while the buttery croissant and melted cheese on top make it feel extra indulgent. It’s a classic-style soup with a fun, comforting twist.

Why You’ll Love This Recipe

I love this recipe because it delivers bold, slow-cooked flavor with simple ingredients. I enjoy how the mushrooms add extra depth and heartiness, making the soup feel even more satisfying. The cheesy croissant topping is one of my favorite parts, since it’s softer and richer than traditional bread while still soaking up all that delicious broth.

Ingredients

(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)

yellow onions, thinly sliced
mushrooms, sliced
olive oil
butter
garlic, minced
all-purpose flour
beef broth or vegetable broth
dry white wine (optional)
fresh thyme
fresh rosemary
bay leaf
salt
black pepper
croissants, sliced
gruyère or swiss cheese, shredded

Directions

I start by heating olive oil and butter in a large pot over medium heat. I add the sliced onions and cook them slowly until deeply caramelized, stirring often. I add the mushrooms and continue cooking until they release their moisture and become golden. I stir in the garlic and flour and cook briefly to remove the raw flour taste. I deglaze the pot with wine if using, then add the broth, thyme, rosemary, bay leaf, salt, and pepper. I let the soup simmer so the flavors can fully develop. To finish, I ladle the soup into oven-safe bowls, top with sliced croissant and shredded cheese, and broil until the cheese is melted and bubbly.

Servings and timing

I usually make this soup to serve 4 people.
Preparation time: about 15 minutes
Cooking time: about 45 minutes
Total time: approximately 1 hour

Variations

I sometimes add a splash of balsamic vinegar for extra depth. When I want a vegetarian version, I use vegetable broth and add extra mushrooms. I also enjoy mixing cheeses like mozzarella and gruyère or adding fresh parsley or chives on top after broiling.

storage/reheating

I store leftover soup without the croissant topping in an airtight container in the refrigerator for up to 4 days. When reheating, I warm the soup on the stovetop and add fresh croissant and cheese before serving. This keeps the topping from becoming soggy. French Onion Soup with Mushrooms, Extra Herbs & Cheesy Croissant Topping

FAQs

Can I make this soup ahead of time?

I often do, since the flavor improves after sitting for a day.

What mushrooms work best?

I like using cremini or baby bella mushrooms for their deep, earthy flavor.

Can I skip the wine?

I do sometimes, and the soup is still rich and flavorful with just broth.

Why use croissants instead of bread?

I love croissants because they add a buttery richness and softer texture.

Can I freeze French onion soup?

I freeze the soup base without toppings for up to 3 months and add the croissant and cheese after reheating.

Conclusion

French onion soup with mushrooms, extra herbs, and a cheesy croissant topping is a comforting, flavorful dish I love making when I want something warm and indulgent. The combination of caramelized onions, savory mushrooms, and rich, cheesy topping makes this soup a standout meal I always look forward to enjoying.

French Onion Soup with Mushrooms, Extra Herbs & Cheesy Croissant Topping

Print Recipe

Pin Recipe

5 Stars 4 Stars 3 Stars 2 Stars 1 Star

No reviews

A rich and comforting twist on classic French onion soup, featuring savory caramelized onions, earthy mushrooms, fragrant herbs, and a buttery croissant and cheese topping. Perfect for cozy, indulgent meals.

Author: Lizaa
Prep Time: 15 minutes
Cook Time: 45 minutes
Total Time: 1 hour
Yield: 4 servings
Category: Soup
Method: Stovetop and Broiling
Cuisine: French
Diet: Vegetarian

Ingredients

4 large yellow onions, thinly sliced
8 oz mushrooms (cremini or baby bella), sliced
2 tbsp olive oil
2 tbsp butter
3 cloves garlic, minced
2 tbsp all-purpose flour
6 cups beef broth or vegetable broth
1/2 cup dry white wine (optional)
1 tsp fresh thyme, chopped
1 tsp fresh rosemary, chopped
1 bay leaf
Salt, to taste
Black pepper, to taste
2 croissants, sliced into rounds or halves
1 1/2 cups shredded gruyère or swiss cheese

Cook Mode Prevent your screen from going dark

Instructions

Heat olive oil and butter in a large pot over medium heat.
Add sliced onions and cook, stirring often, for 25–30 minutes until deeply caramelized.
Add mushrooms and cook until they release moisture and turn golden, about 8–10 minutes.
Stir in garlic and cook for 1 minute. Sprinkle in flour and cook for another 1–2 minutes to eliminate the raw flour taste.
Deglaze with white wine (if using), scraping up any brown bits from the bottom of the pot.
Add broth, thyme, rosemary, bay leaf, salt, and pepper. Bring to a simmer and cook for 15–20 minutes to blend flavors. Remove bay leaf.
Preheat broiler. Ladle soup into oven-safe bowls.
Top each bowl with a slice of croissant and sprinkle with shredded cheese.
Place under broiler until cheese is melted and bubbly, 2–4 minutes.
Serve hot, optionally garnished with fresh herbs like parsley or chives.