Classic French Onion Soup Gratinée: A Comforting Bowl of Cheesy Goodness

I first experienced authentic French onion soup at a small bistro in Paris during a snowy December evening. The waiter brought a steaming crock covered with a glorious crown of golden, bubbling cheese that stretched dramatically as he set it down. That first spoonful, breaking through the cheesy crust into the rich broth below, created a food memory I’ve been trying to recreate ever since.

Onion Soup Gratinée is the ultimate comfort food: sweet caramelized onions swimming in a rich beef and chicken broth, topped with crusty bread and a generous blanket of melted Gruyère cheese. This classic French recipe transforms humble ingredients into something extraordinary that warms both body and soul.

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What Makes This Recipe Special

Onion soup gratinée might sound fancy, but it delivers extraordinary flavor through simple elements:

• Simple, Affordable Ingredients: Transforms basic pantry staples into a gourmet experience
• Slow Caramelization Process: Patience turns ordinary onions into sweet, golden strands of flavor
• Dual Stock Approach: Combining beef and chicken stocks creates a more complex flavor profile
• Traditional Technique: Following classic French methods ensures authentic results
• Instagram-Worthy Presentation: The bubbling, golden cheese topping creates that perfect “cheese pull” moment

The crowning glory is, of course, the gratinée topping. The term “gratinée” refers to a crispy topping of melted cheese or breadcrumbs, creating that irresistible cheesy pull that makes this soup so visually appealing and delicious.

Ingredients: What Each One Brings to the Dish

• Onions – The star of the show, they caramelize to create sweet, deep flavor and provide body to the soup
• Unsalted Butter – Provides richness and helps onions caramelize more effectively than oil
• White Wine – Adds acidity and deglazes the pan, lifting all the flavorful browned bits from caramelizing
• Chicken Stock – Brings a light, aromatic base note to balance the richness
• Beef Stock – Provides deep, savory umami flavor and rich color
• Fresh Thyme – Contributes earthy, slightly floral notes that complement the sweetness of the onions
• Bay Leaf – Adds subtle complexity and depth to the broth
• French Bread – Serves as a vehicle for the cheese while soaking up the delicious broth
• Gruyère Cheese – Creates that perfect melty, stretchy topping with a nutty flavor
• Salt – Enhances all the flavors and balances sweetness
• Black Pepper – Adds subtle heat and complexity

Choosing the Best Onions

The type of onion you select will impact the final flavor profile of your soup:

• Sweet Onions: Offer the perfect balance of sweetness and mellowness
• Yellow Onions: Provide bright flavor with mild bitterness and underlying sweetness
• Red Onions: Create a deeper flavor with slightly bitter notes
• Shallots: Deliver excellent sweetness with bright, rich undertones

For the most complex flavor, consider using a blend of different varieties. My favorite combination is three large yellow onions with one sweet onion added for extra dimension.

How to Make Onion Soup Gratinée

This onion soup is not difficult to make, though you need patience waiting for the onions to caramelize. Here are the instructions in brief:

1. Melt butter in a large saucepan or Dutch oven.
2. Add the onions and cook until they are caramelized.
3. Deglaze with wine and reduce. 
4. Add the two stocks, thyme, and bay leaf. Stir to combine.
5. Bring to a boil over medium-high heat, then reduce the heat to low and simmer for 30 minutes. Adjust taste as desired. Discard the bay leaf.

5. Pour soup into individual bowls.
6. Toast the bread and place it on top of the soup.
7. Cover with cheese. 
8. Place under the broiler until the cheese is golden brown.
9. Serve it with a sprinkle of chopped fresh herbs or place sprigs of fresh thyme on top.

French Onion Soup Gratinée – Variations

• Wine: This onion gratin soup recipe uses white wine. However, you can also use red wine or a blend of vermouth (a fortified wine) and brandy.

Note: Vermouth is great to have on hand. It’s perfect for deglazing or making a quick sauce. It also keeps well, which means it’s not necessary to open a bottle of wine when you need wine in a recipe. 

• Cheese: Instead of gruyère, you could go with Swiss, mozzarella, or Asiago.
• Bread: Slices of baguette or Italian bread work just as well as French bread. You can also use croutons.

How to Get the Best Caramelized Onions

Let’s start with one immutable fact: onions do not caramelize quickly! This is because the aim of caramelizing onions isn’t just to brown the surface; it’s to transform the onions so they’re soft and sweet to the core. So, if you want the best caramelized onions, take it slowly – at least an hour!

Butter produces much more delicious caramelized onions than oil and also kicks off the browning reaction more quickly.

As for cooking vessels, you will get the best results in cast iron or carbon steel, with stainless steel a close second. Onions are much slower to brown in an enameled pot.

Make ahead tip: Caramelize your onions the day before and refrigerate.

Tip for Toasting the Bread

Preheat your oven’s broiler and set a rack about 6 inches under the heat source. Arrange the bread slices on a baking sheet and broil, turning once, until well toasted on both sides (about 3 minutes). 

How to Fill Soup Crocks

Ladle the hot soup into the crocks for individual portions until they are almost full. Allow enough space at the top so that when you add the bread, it’s flush with the top of the bowl.

Place 2 slices of bread on each crock to fully cover the top (it may be necessary to break up the pieces). Arrange cheese slices or grated cheese so the cheese covers the bread and hangs somewhat over the sides.

Double up the cheese for an extra decadent cheese pull – you won’t regret it!

What to Serve With Onion Gratin Soup

French onion soup au gratin is so rich and hearty that you might wonder what to serve with it. Here are some ideas:

• The holy grail of entrées is steak, which is perhaps the best thing you can serve after a bowl of French onion au gratin soup.
• If you want something a bit lighter, scallops are big, meaty chunks of heaven that taste great.
• Baked salmon also goes well with French onion gratin soup. This fatty pink fish is not too heavy and perfectly balances the soup’s richness.
• Pork tenderloin is a simple but super-effective dinner to serve after a hearty bowl of French onion soup.

Storage and Reheating Instructions

Refrigerator Storage

• Store soup base (without bread and cheese) in airtight containers for up to 3 days
• Use containers with tight-fitting lids to contain the strong onion aroma
• Allow soup to cool completely before refrigerating to maintain quality

Freezer Storage

• Cool soup completely before freezing to prevent ice crystals
• Portion into freezer-safe containers or heavy-duty freezer bags
• Leave ½ inch headspace in containers for expansion
• Freeze for up to 3 months for the best quality
• Label with date and contents
• For easy individual servings, freeze in 1½ cup portions

Reheating From Refrigerated

1. Transfer to a saucepan and heat over medium-low until hot (5-7 minutes)
2. Meanwhile, prepare fresh bread and cheese toppings
3. Assemble and broil as directed in the original recipe

Reheating From Frozen

• Add fresh bread and cheese toppings just before serving
• Thaw overnight in the refrigerator (preferred method)
• Heat gently on the stovetop until thoroughly hot (10-15 minutes)

More French Onion Soup Recipes

• Applebee’s French Onion Soup
• Brown Derby French Onion Soup
• Homemade Classic French Onion Soup
• Panera French Onion Soup
• TGI Friday’s French Onion Soup

French Onion Inspired Recipes

• French Onion Burger
• Hot French Onion Dip

Favorite Soup Recipes

• Beef Tortilla Soup
• Celery Soup
• Creamy Chicken Tortellini Soup
• Old Fashioned Potato Soup
• Olive Garden Toscana Soup
• Panera Tomato Soup

Check out more of my easy soup recipes and the best recipes for winter on CopyKat!

Recipe source: Le Cafe Ile St. Louis