Save This decadent soup brings together the best of French onion and creamy mushroom in one pot. Each spoonful is silky from the broth and cream with sweet layers of caramelized onion and savory mushrooms. It is perfect for those evenings when you crave comfort with just a hint of luxury.
The first time I made this my entire house filled with the smell of sweet onions and earthy mushrooms. It quickly became my go:to when I needed a hug in a bowl.
Ingredients
- Yellow onions sliced thin: Bring deep sweetness after slow caramelizing. Use firm onions without bruises for best results.
- Cremini or button mushrooms: Add savory umami depth. Choose brown, firm mushrooms and lightly wipe away dirt before slicing.
- Garlic minced: Gives subtle warmth and aromatics.
- Celery finely chopped: Balances the richness with a fresh undertone.
- Unsalted butter: For rich flavor and golden onions. European:style butter adds extra creaminess if you have it.
- Heavy cream: Blends into the base for a velvety mouthfeel.
- Vegetable broth: Forms the heart of the soup. Choose low:sodium for more control over final flavor.
- Dry white wine: Adds brightness and complexity. Pick a crisp, unoaked bottle that you would enjoy drinking.
- Fresh thyme: Adds a classic herbal note. Dried thyme works if fresh is not on hand.
- Bay leaf: Infuses subtle layers of flavor. Remove before serving.
- Salt and freshly ground black pepper: Heighten all the natural flavors.
- Baguette slices: Pack classic French onion character. Look for bread with a crackling crust.
- Gruyère or Swiss cheese grated: For the gratinée top brings a nutty richness. Use a block and grate fresh for best melt.
- Fresh parsley chopped: For garnish brightening every bowl.
Instructions
- Sauté the Onions:
- Place your largest heavy pot over medium:low heat. Melt butter until foaming. Tumble in the onions with a pinch of salt which coaxes out their juices. Stir every few minutes and let the onions slowly caramelize for twenty five to thirty minutes until they are deep golden and very soft. Do not rush this as gentle caramelizing unlocks all their sweetness.
- Build the Flavor Base:
- Once the onions look jammy and golden add minced garlic and chopped celery. Sauté for about two minutes so the garlic becomes fragrant and celery just softens. At this stage everything should smell wonderfully aromatic.
- Brown the Mushrooms:
- Stir in the sliced mushrooms. Raise the heat slightly. Cook and stir for eight minutes until mushrooms lose moisture and take on color. Do not crowd the pan or the mushrooms may steam instead of browning.
- Deglaze with Wine:
- Pour in dry white wine if using. Scrape up all the flavor stuck at the bottom of the pot. Let the wine bubble for two minutes until reduced by half which deepens flavor without leaving alcohol.
- Simmer with Broth and Herbs:
- Add the broth thyme and bay leaf. Stir everything together and bring to a gentle simmer. Let the soup bubble uncovered for ten minutes. This allows all the flavors to blend and the liquid to concentrate.
- Enrich with Cream:
- Fish out the bay leaf. Lower the heat as much as possible and pour in the heavy cream. Warm slowly for two to three minutes so that the soup becomes silky but never bubbles rapidly. Season thoughtfully with salt and black pepper.
- Classic Gratinée Finish:
- If you want a true French onion finish ladle the soup into oven:proof bowls. Place a toasted baguette slice over each bowl and blanket with Gruyère cheese. Place under the broiler until the cheese is bubbling and golden with crisp edges.
- Garnish and Serve:
- Shower each bowl with chopped parsley for freshness right before serving. The herbs add color and bring the whole pot to life.
Save Every time I prepare this soup my favorite moment is watching the onions slowly transform. Their deep golden color and aroma make the kitchen feel so inviting and always reminds me of Sunday afternoons when my family would gather around for a warming meal.
Storage Tips
Keep leftovers in an airtight container in the fridge for up to four days. The flavors intensify after a day's rest and the soup reheats beautifully on the stove over low heat. For longer storage freeze soup without bread or cheese for up to two months. Thaw in the fridge before reheating gently and add fresh cream or parsley just before serving.
Ingredient Substitutions
Use olive oil and coconut cream for a dairy:free version. If Gruyère is not available Swiss or any sharp melting cheese works wonderfully. For a gluten:free soup use gluten:free bread or simply skip the gratinée finish. If you want even more savoriness a dash of vegetarian Worcestershire sauce or a splash of sherry vinegar can add depth.
Serving Suggestions
Pair this soup with a simple green salad topped with bitter greens or apples for freshness. For heartier appetites serve alongside a slice of rustic sourdough or a handful of garlic croutons. It is also wonderful as a first course for a wintry dinner party followed by roast vegetables or a main of your choice.
French Roots
This soup draws from two beloved classics of French cuisine:onion soup and creamy mushroom soup. Caramelized onions are a staple in French country cooking bringing sweetness and body to many dishes. The gratinée finish with bread and cheese is a tradition started in Parisian bistros adding a bubbly layer to soups on cold days.
Seasonal Adaptation Tips
Swap in baby leeks for onions in spring for a more delicate flavor Add wild or foraged mushrooms in autumn for a woodsy twist Lighten with half cream and half milk in warmer months for an airier texture
Success Stories
Several friends tried this soup with vegan swaps and were amazed at the silkiness from coconut cream. One reader told me her kids now ask for mushroom onion soup instead of tomato on chilly nights.
Freezer Meal Conversion
Prepare soup through simmering with broth and herbs but stop before adding cream. Cool and freeze in portions. When you are ready to eat thaw gently reheat and finish with cream for a soup that tastes freshly made.
Save A pot of this soup always brings comfort and warmth plus it elevates even a simple weeknight to something special. Share with loved ones and savor every spoonful.
Recipe FAQ Section
- → How do I properly caramelize onions for this soup?
Slice onions evenly and cook them in butter over medium-low heat, stirring often, until deeply golden and sweet. This takes about 25–30 minutes.
- → Can I make this soup vegan?
Use olive oil and coconut cream instead of butter and heavy cream, and skip the cheese or use a vegan substitute for serving.
- → Is wine necessary in the soup?
Wine adds depth and flavor, but you can omit it if preferred or use a splash of sherry vinegar for brightness.
- → What’s the classic way to serve French onion soup?
Ladle the soup into oven-ready bowls, top with toasted baguette and grated Gruyère, then broil until bubbly and golden brown.
- → Which mushrooms are best for this dish?
Cremini or button mushrooms work well, offering earthy flavor and a tender texture that complements the caramelized onions.
- → How can I enhance the flavor further?
Try adding Worcestershire sauce (vegetarian if needed), a splash of sherry vinegar, or fresh herbs to deepen and round out the taste.