If you are searching for a comforting and unforgettable meal, this Mushroom & Caramelized Onion Soup with Cheesy Toasties Recipe is an absolute must-try. It brings together deeply caramelized onions, earthy cremini mushrooms, and a rich broth that sings with flavor. Topped with irresistibly cheesy, golden toasties, every spoonful offers a warm hug in a bowl. This cozy combination makes it perfect for chilly evenings or whenever you need a pick-me-up food that’s comforting, elegant, and utterly satisfying.
Ingredients You’ll Need
Gathering these simple yet essential ingredients is your first step toward creating a soul-satisfying dish. Each one plays a critical role, whether it’s building layers of flavor, adding depth, or enhancing the texture and color of the soup and toasties.
- Unsalted butter (4 tbsp plus 1 tbsp): Essential for caramelizing onions and sautéing mushrooms to a flavorful golden brown.
- Yellow onions (4 large, thinly sliced): The star for a deeply sweet, caramelized base that enriches the entire soup.
- Garlic (3 cloves, finely chopped): Adds aromatic warmth and subtle punch to both soup and mushrooms.
- Bay leaves (2): Infuse the broth with an earthy, herbal undertone.
- Fresh thyme (2 sprigs plus 1 tsp): Provides a fresh woodsy aroma that complements mushrooms beautifully.
- Dry white wine (1 cup): Used to deglaze and add acidity that balances the richness.
- All-purpose flour (¼ cup): Thickens the broth to a luscious consistency.
- Beef or vegetable broth (8 cups): Forms the hearty, flavorful liquid base of your soup.
- Salt and pepper: Vital for seasoning and bringing out perfect balance.
- Olive oil (1 tbsp): Used alongside butter to sauté mushrooms without burning.
- Cremini mushrooms (24 oz, quartered): Offer earthy depth and meaty texture to the soup.
- Baguette (sliced): Crispy vehicle for your melty, cheesy toppings.
- Gruyère cheese (8 oz, grated): Melts beautifully for those luscious, gooey toasties.
- Parmesan cheese (½ cup, grated): Adds sharpness and a lovely golden crust when broiled.
How to Make Mushroom & Caramelized Onion Soup with Cheesy Toasties Recipe
Step 1: Caramelize the Onions
Start by melting butter in a large pot over medium-low heat. Toss in your thinly sliced yellow onions along with bay leaves, thyme sprigs, and a pinch of salt. This step takes patience—cook slowly for 30 to 40 minutes, stirring occasionally, until the onions turn a deep golden brown and develop that sweet, jammy flavor. This is the soul of the soup, where all the magic begins.
Step 2: Add Garlic and Deglaze
Once your onions are beautifully caramelized, stir in the finely chopped garlic so its aroma evenly infuses the pot. Then pour in the dry white wine to deglaze, scraping up any flavorful bits stuck to the pot’s bottom. Simmer until the wine has reduced and thickened, which helps concentrate the flavors even more.
Step 3: Thicken and Simmer the Soup
Sprinkle in the all-purpose flour and cook it for about 2 minutes while stirring to avoid lumps. Then, whisk in the beef or vegetable broth gradually until smooth. Bring this mixture to a gentle simmer and let it cook for 20 to 25 minutes. This simmering melds the flavors beautifully and allows the broth to thicken into a perfect, silky texture.
Step 4: Sauté the Mushrooms
While the soup simmers, heat the butter and olive oil in a skillet over medium heat. Add the remaining garlic and let it release its fragrance, then toss in the quartered cremini mushrooms and fresh thyme. Cook for 10 to 12 minutes, stirring occasionally, until the mushrooms are browned and tender. This step adds a delicious meaty texture and deep umami flavor that is signature to this Mushroom & Caramelized Onion Soup with Cheesy Toasties Recipe.
Step 5: Prepare the Cheesy Toasties
Toast the sliced baguette either in a toaster or oven until just crispy. Pile the toasted slices high with the grated Gruyère and Parmesan cheeses. Then broil them for a few minutes, watching closely, until the cheese melts and bubbles into a golden, irresistible crust. These cheesy toasties will crown your soup with a crunchy, gooey, and cheesy finish.
Step 6: Serve It Up
Ladle the rich mushroom and caramelized onion soup into bowls. Top each with one or two cheesy toasties and garnish with a sprinkle of fresh thyme and additional Parmesan if you like. This final touch elevates the presentation and flavor, making every spoonful extraordinary.
How to Serve Mushroom & Caramelized Onion Soup with Cheesy Toasties Recipe
Garnishes
A sprinkle of fresh thyme leaves brightens the warm, rich flavors, while an extra dusting of Parmesan adds a lovely salty touch. For a pop of color and subtle freshness, a few chopped chives or a drizzle of truffle oil can also be stunning additions.
Side Dishes
Although the soup is quite hearty on its own, pairing it with a crisp green salad or a lightly dressed arugula salad balances the richness perfectly. A glass of dry white wine or a rich, malty beer also complements the earthy mushrooms and caramelized onions beautifully.
Creative Ways to Present
Serve the soup in rustic crocks with the cheesy toasties perched on top or on the side for dipping. For special occasions, you can ladle the soup into small ramekins and toast the mini cheesy toasts for an elegant appetizer. Adding edible flowers or microgreens on the toasties creates a delightful, Instagram-worthy presentation.
Make Ahead and Storage
Storing Leftovers
This soup keeps beautifully in the refrigerator for up to three days. Store it in an airtight container, and keep the cheesy toasties separate to avoid sogginess. When ready to enjoy, reheat the soup gently on the stove over low heat.
Freezing
You can freeze the soup (without the toasties) for up to two months. Use freezer-safe containers, leaving space at the top as it expands. Thaw it slowly in the fridge overnight before reheating for the best texture and flavor.
Reheating
Reheat the soup on the stove over medium-low heat, stirring occasionally. To bring back the crispness of the cheesy toasties, re-toast them briefly under the broiler or in a hot oven just before serving.
FAQs
Can I use other types of mushrooms?
Absolutely! While cremini mushrooms offer great depth and texture, you can mix in shiitake, portobello, or button mushrooms for varied flavor and complexity.
Is it okay to use vegetable broth instead of beef broth?
Yes, vegetable broth is a wonderful vegetarian option that still delivers plenty of flavor. Just make sure to choose a rich, high-quality broth for the best result.
Can I make this recipe dairy-free?
To make a dairy-free version, substitute butter with olive oil or vegan margarine and use a dairy-free cheese or skip the cheesy toasties altogether. The soup itself will still be delicious and comforting.
How long does it take to caramelize the onions properly?
Plan for about 30 to 40 minutes on low heat. Patience is key here because slow cooking allows the onions to develop their sweet, rich flavor without burning.
Can I prepare the soup in advance and assemble the toasties later?
Definitely! Preparing the soup ahead and making the toasties fresh before serving ensures both elements taste their best with that perfect combination of hot, melty cheese and hearty soup.
Final Thoughts
This Mushroom & Caramelized Onion Soup with Cheesy Toasties Recipe is one of those treasured dishes that feels like a warm, welcoming friend on a chilly evening. The harmonious blend of sweet caramelized onions, earthy mushrooms, and gooey cheese on crispy toasties creates a meal that’s simple yet completely satisfying. I encourage you to try making it soon—you’ll find it’s a wonderful way to turn basic ingredients into something truly special that everyone will love.
Print
Mushroom & Caramelized Onion Soup with Cheesy Toasties Recipe
- Prep Time: 20 minutes
- Cook Time: 1 hour
- Total Time: 1 hour 20 minutes
- Yield: 6 servings
- Category: Soup
- Method: Stovetop
- Cuisine: French-inspired
- Diet: Vegetarian
Description
This hearty Mushroom & Caramelized Onion Soup with Cheesy Toasties is a comforting and flavorful dish perfect for cozy meals. Slowly caramelized onions and sautéed cremini mushrooms create a rich base, enhanced by fresh thyme and a splash of dry white wine. Thickened with flour and simmered in beef or vegetable broth, the soup is served with crispy, cheesy baguette toasties topped with Gruyère and Parmesan cheeses, broiled to golden perfection.
Ingredients
Soup Base
- 4 tbsp unsalted butter
- 4 large yellow onions, thinly sliced
- 2 cloves garlic, finely chopped
- 2 bay leaves
- 2 sprigs fresh thyme
- 1 cup dry white wine
- ¼ cup all-purpose flour
- 8 cups beef broth (or vegetable broth)
- Salt & pepper, to taste
Mushrooms
- 1 tbsp unsalted butter
- 1 tbsp olive oil
- 1 clove garlic, finely chopped
- 24 oz cremini mushrooms, quartered
- 1 tsp fresh thyme
Cheesy Toasties
- 1 baguette, sliced
- 8 oz Gruyère cheese, grated
- ½ cup Parmesan cheese, grated
Instructions
- Caramelize Onions: Melt 4 tablespoons of unsalted butter in a large pot over medium heat. Add the thinly sliced onions, bay leaves, thyme sprigs, and a pinch of salt. Cook slowly, stirring occasionally, for 30–40 minutes until the onions turn a deep golden brown and are fully caramelized.
- Add Garlic and Deglaze: Stir in the finely chopped garlic and cook briefly until fragrant. Pour in the dry white wine to deglaze the pot, scraping up any browned bits. Allow the wine to simmer and reduce until mostly evaporated.
- Add Flour and Broth: Sprinkle the all-purpose flour over the onion mixture and cook for 2 minutes, stirring constantly. Gradually whisk in the beef or vegetable broth to avoid lumps. Bring the soup to a simmer and cook for another 20–25 minutes to let the flavors meld and the soup thicken slightly.
- Sauté Mushrooms: In a separate skillet, heat 1 tablespoon unsalted butter and 1 tablespoon olive oil over medium-high heat. Add the chopped garlic, then the quartered cremini mushrooms and fresh thyme. Sauté for 10–12 minutes until the mushrooms are nicely browned and have released their moisture.
- Prepare Cheesy Toasties: Toast the sliced baguette pieces until crisp. Top each slice with grated Gruyère and Parmesan cheeses. Place under the broiler for a few minutes until the cheese melts, bubbles, and turns golden brown.
- Serve: Ladle the hot soup into bowls and top with the mushroom mixture. Garnish each serving with a cheesy toastie, a sprinkle of fresh thyme, and some extra Parmesan cheese if desired.
Notes
- Use vegetable broth instead of beef broth to make this recipe vegetarian.
- Cooking the onions low and slow is key to developing their rich caramelized flavor.
- Broil the toasties carefully to avoid burning—watch them closely as they can brown quickly.
- Gruyère cheese adds a nutty flavor; you can substitute Swiss or mozzarella if preferred.
- Leftover soup can be refrigerated for up to 3 days; reheat gently on the stovetop.
