Soups & Stews
America's Test Kitchen's French onion soup delivers the restaurant-quality depth and texture you crave, with perfectly caramelized onions and a golden, crispy bread top. The secret lies in slow, patient cooking that transforms onions into sweet, jammy layers while building a rich, savory broth.
I've refined this recipe over years of testing, ensuring every element comes together for maximum flavor and that signature crispy finish.
This method focuses on precision—starting with thinly sliced onions that cook down for hours until deeply caramelized, then combining them with a flavorful beef broth and aromatic herbs.
The bread topping is the star: toasted until crispy, then topped with melted Gruyère cheese that turns bubbly and golden under the broiler. It's the kind of dish that feels indulgent yet comes together with methodical technique.
The result is a bowl of French onion soup where each spoonful delivers layers of sweet, savory, and umami flavors, all topped with a perfectly crispy bread crust. The caramelized onions add depth, the broth provides richness, and the cheese adds a creamy, melty finish.
This is comfort food at its finest—warm, inviting, and impossible to resist.
Whether you're serving this classic to guests or treating yourself, the key is patience and attention to detail. The slow caramelization transforms simple onions into something extraordinary, while the crispy bread top ensures every bite is satisfying.
Ready to make this iconic dish at home? Let's get started with the ingredients and step-by-step instructions.
Ingredients for america's test kitchen french onion soup
The foundation of this iconic soup lies in these carefully chosen ingredients, each playing a crucial role in creating restaurant-quality depth.
| Ingredient | Amount | Notes |
|---|---|---|
| Yellow Onions 🧅 | 4 lb | Thinly sliced, peeled |
| Beef Broth 💧 | 6 cups | Homemade or high-quality store-bought |
| Dry White Wine 🍷 | 1 cup | Dry, full-bodied variety |
| Unsalted Butter 🧈 | ½ cup | Cold, cubed for caramelizing |
| Fresh Thyme 🌿 | 1 tbsp | Leaves only, chopped |
| Fresh Rosemary 🌿 | 1 tbsp | Leaves only, chopped |
| Garlic Cloves 🧄 | 4 cloves | Minced for broth |
| Salt 🧂 | 1 ½ tsp | Kosher or sea salt |
| Black Pepper 🌶️ | ½ tsp | Freshly ground |
| Sourdough Bread 🍞 | 1 lb | Baguette-style, crust removed |
| Gruyère Cheese 🧀 | 1 cup | Freshly grated, aged |
| Extra-Virgin Olive Oil 🫒 | 2 tbsp | For finishing |
The yellow onions are non-negotiable—this recipe demands 4 pounds of them, thinly sliced to maximize surface area for caramelization. Whole Foods or Trader Joe's often carry pre-sliced options, but I prefer slicing them myself for precision. Look for onions with dry, papery skins and firm flesh; avoid any with soft spots or sprouting. The Gruyère cheese should be aged at least 6 months—you'll taste the difference in the melt and flavor. Murray's Cheese or local specialty shops are great sources for authentic Gruyère. For the beef broth, I recommend making a batch from scratch using beef bones and aromatic vegetables, but a high-quality store-bought version like Kitchen Basics or Pacific Foods works in a pinch.
No dry white wine? Substitute with extra beef broth, but reduce the total liquid by 1 cup to maintain balance. The fresh thyme and rosemary can be swapped for 1 teaspoon dried thyme and 1 teaspoon dried rosemary, but fresh herbs add a brightness that dried can't match. For the sourdough bread, a baguette-style loaf is ideal—if you can't find sourdough, French bread works just as well. The Gruyère can be replaced with Comté for a similar melt, though the flavor will differ slightly. If you're short on time, pre-minced garlic is fine, but freshly minced garlic adds an extra layer of flavor that's worth the 30 seconds it takes.
The caramelized onions keep for 5 days in the fridge, covered tightly—reheat gently in the broth to maintain their jammy texture. The Gruyère cheese should be stored in its original packaging to prevent drying out, and used within 2 weeks of opening. For the sourdough bread, toast the slices ahead of time and store them in an airtight container at room temperature for up to 3 days. If making the soup ahead, assemble it just before baking—this ensures the bread topping stays crispy. Leftovers can be refrigerated for 3 days, but the bread topping loses its crispness, so it's best enjoyed fresh.
Why You'll Love This Recipe
- One-Pot Magic: I swear by this recipe because it’s actually one-pot—no extra bowls, no messy saucepans. Just caramelized onions, a splash of wine, and simmering beef broth until it’s rich enough to make you forget you didn’t slave over it.
- Wine Infusion Win: That dry white wine isn’t just for show—it cuts through the sweetness of the onions and deepens the broth into something ridiculously flavorful. (Pro tip: Save the leftover wine for the next batch.)
- Crowd-Pleaser Flex: Whether it’s a chilly Tuesday night or a dinner party, this soup delivers. Serve it with crusty bread for a cozy meal, or add a grilled cheese on top for a next-level comfort dish. (My roommates still ask for it weekly.)
- Budget-Friendly Leftovers: The broth is so rich you’ll want to make a double batch—perfect for reheating or freezing. Plus, onions and beef broth are cheap staples, so you’re basically making gourmet soup on a shoestring. (Yes, even on a student budget.)
Step-by-step instructions for america's Test Kitchen French onion soup
Master the art of deep caramelization and crispy bread topping for restaurant-quality results.
Caramelize the Onions Slowly
Heat the 0.5 cup unsalted butter in a large Dutch oven over medium-low heat. Add the 4 lb yellow onions, sliced thinly, and spread them out in an even layer. Cook undisturbed for 45 minutes, stirring only when you notice the edges begin to brown. This slow process transforms the onions into sweet, golden caramel.
After 45 minutes, add the 1 tbsp fresh thyme and 1 tbsp fresh rosemary, stirring to distribute the herbs evenly. Continue cooking for another 30 minutes, stirring occasionally, until the onions are deep golden brown and nearly jam-like in texture. This is where the magic happens—patience is key to developing that rich, complex flavor. If the onions start to stick, reduce the heat slightly and continue cooking.
Build the Rich Broth Base
Push the caramelized onions to one side of the Dutch oven and add the 4 cloves minced garlic to the empty space. Cook for 30 seconds until fragrant, then pour in the 1 cup dry white wine, scraping up any browned bits from the bottom. Let the wine simmer for 2-3 minutes until mostly evaporated.
Add the 6 cups beef broth, bring to a simmer, and stir to combine everything. Add the 1.5 tsp salt and 0.5 tsp black pepper, then reduce heat to medium-low. Let the soup simmer uncovered for 30 minutes, allowing the flavors to meld and the broth to deepen. The onions should be fully immersed, and the broth should be rich and aromatic. Taste and adjust seasoning if needed—this is your foundation.
Prepare the Crispy Bread Topping
Preheat your broiler to high. Remove the crust from the 1 lb sourdough bread and cut it into 1-inch thick slices. Brush both sides of each slice with 2 tbsp extra-virgin olive oil to ensure crispiness. Arrange the slices on a baking sheet in a single layer, leaving space between them.
Broil the bread for 2-3 minutes per side until golden brown and crispy. Watch closely—they burn quickly. Remove from the oven and immediately sprinkle each slice with ¼ cup gruyère cheese, dividing evenly. Return to the broiler for 1-2 minutes until the cheese melts and bubbles. The bread should be crispy on the outside with gooey cheese inside—this is the moment that matters.
Assemble and Serve
Ladle the hot soup into 4 oven-safe bowls, dividing the onions and broth evenly. Place 1 cheese-topped bread slice on top of each bowl, pressing down gently to help it crisp up further. Broil for 1-2 minutes until the cheese is bubbly and the bread is extra crispy. Serve immediately while the bread is still hot and the cheese is melty.
This is where the dish shines—crispy bread contrasts perfectly with the velvety soup. The caramelized onions should be tender yet still hold their shape, and the Gruyère should stretch beautifully when you cut into it. Each bite delivers layers of flavor, from the deep caramel to the rich broth and crispy, cheesy bread. Enjoy while warm!
Pro Tips For Making America'S Test Kitchen French Onion Soup
- Sweat, Don’t Burn: The onions should caramelize slowly—aim for 45-60 minutes at medium-low heat, stirring occasionally. I learned this the hard way: rushing it turns them bitter, and you’ll end up with a sad, dark sludge instead of golden, jammy layers.
- Salt the Broth: The recipe calls for unsalted butter and broth, so taste the broth before adding wine or thyme—adjust salt now, not later. I used to skip this, and the soup always ended up bland, no matter how much I seasoned at the end.
- Deglaze with Wine: After browning the onions, pour in the white wine all at once and let it bubble hard for 2-3 minutes to lift all the fond from the pot. Skimping here leaves a dull, sticky residue that ruins the depth of flavor.
- Toast the Thyme: Strip the thyme leaves and fry them in the butter for 30 seconds before adding onions—this releases their oils and makes the soup smell like a Parisian bistro. (Yes, even if you’re impatient like me, wait those 30 seconds.)
Make-ahead tips for this dish
Prep Ahead Secrets
Caramelize the onions 2 days in advance—they keep beautifully in an airtight container in the fridge. Reheat them gently in the broth to maintain their jammy texture. I like to make a big batch and freeze half for future soups. 🧅
Prepare the broth base 1 day ahead and store it in the fridge. The flavors deepen overnight, and you can simply reheat it when ready to assemble. If using store-bought broth, choose a high-quality brand like Kitchen Basics for the best results.
Bread Prep Shortcut
Toast the bread slices up to 3 days ahead and store them in an airtight container at room temperature. When ready to serve, just reheat them in the broiler for 1-2 minutes to restore crispness. This saves time without sacrificing texture.
Cheese Prep Tips
Grated Gruyère keeps for 2 weeks in the freezer, making it easy to have on hand. Use a microplane for the freshest grate—it yields more cheese and melts better. If you’re short on time, pre-grate the cheese and store it in the fridge until ready to use.
Assemble Just Before Serving
The bread topping loses crispness if assembled ahead, so wait until the last 10 minutes before serving. Ladle the hot soup into bowls, top with cheese-covered bread, and broil until bubbly. This ensures the bread stays crispy and the cheese melts perfectly. ⏰
Freezer-Friendly Option
For a make-ahead freezer meal, assemble the soup without the bread topping and freeze it in airtight containers for up to 3 months. When ready to serve, reheat the soup and toast fresh bread slices, then add the cheese and broil as directed.
The texture won’t be identical, but it’s still delicious!
Nutrition facts
Frequently asked questions
Can I use vegetable broth instead of beef broth for a vegetarian version?
For a vegetarian twist, replace the beef broth with a rich vegetable broth and omit the wine entirely. Use 1 cup dry white wine substitute (like apple cider or extra broth) to maintain depth. Add 1 tsp soy sauce to the broth for umami complexity that mimics beef's savory notes. The caramelized onions and Gruyère will still shine, delivering a satisfying vegetarian version.
How do I prevent the bread from getting soggy under the cheese?
Start with perfectly crispy toasted bread—this is your secret weapon. Brush both sides with olive oil before broiling, then toast until golden brown. The key is broiling the cheese-topped bread for just 1-2 minutes—watch closely! If the bread softens too quickly, reduce broil time. For extra insurance, sprinkle bread with 1/4 tsp cornstarch before adding cheese to create a barrier.
What's the best way to reheat leftovers without losing crispiness?
Reheat only the soup portion (without bread) in a saucepan over medium-low heat until steaming. For the bread topping, toast fresh slices separately in the broiler for 2-3 minutes until crispy, then add cheese and broil 1 minute to melt. Never microwave the bread—it'll turn rubbery. This two-step process keeps textures perfect.
Can I make this soup in a slow cooker?
While possible, the slow cooker won't achieve the same deep caramelization. For best results, caramelize the onions on the stovetop first, then transfer everything to the slow cooker on low for 2 hours. The broth will develop flavor, but the onions won't get as jammy. For the bread topping, follow the broiler method—it's the only way to get that signature crispiness.
Why does my soup taste bland compared to restaurant versions?
Restaurant versions often use homemade stock and slow-cooked onions for hours. Boost flavor by:
- Using high-quality broth (homemade or premium brands),
- Adding 1 tsp fish sauce to the broth for depth, and
- Tasting as you go—adjust salt in 1/4 tsp increments. The wine reduction step is critical—don't skip it! Also ensure your Gruyère is aged (6+ months) for maximum flavor impact.