Traditional French Onion Soup Gratinée

Name: Traditional French Onion Soup Gratinée
Prep time: 15 min
Cook time: 1 h 10 min
Total time: 1 h 25 min
Cuisine: France
Ingredients: 1000 g of onions (thinly sliced); 40 g of butter; 1 tbsp of olive oil; 25 g of flour; 150 ml of white wine (dry); 1200 ml of beef broth (hot); 1 tsp of salt; 1/2 tsp of black pepper (ground); 8 slices of country bread (stale); 150 g of gruyère (shredded); 2 tbsp of parsley (chopped)

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This French onion soup gratinée, a must-have Parisian bistro recipe, wins you over with its fragrant broth and crunchy cheese croutons. Perfect as a winter starter or a comforting dinner, it brings authentic warmth to your table.

Total time: 1 h 25
Prep: 15 min
Cook: 1 h 10
Difficulty: Medium
Per person: €1.88

By the CookinBreak team

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Nutrition facts

per serving · estimate

535kcal

Protein20 g15%
Carbs60 g45%
Fat24 g40%
Fiber4 g

Share of each nutrient in the calories of one serving.

Good to know

Chef's tip

Success comes down to caramelizing the onions slowly without burning them. Take your time over low heat: it is the concentration of the natural sugars that gives this amber color and incomparably deep flavor, with no need to add sugar.

Freezing : Can you freeze this recipe?

Yes

The soup base freezes very well, up to 3 months in airtight bags or containers. Add bread and cheese after thawing and reheating.

Storage : How long does it keep?

The soup base keeps 3 to 4 days max in an airtight container in the fridge. The gratin topping (bread, cheese) should be added just before serving.

Making ahead : Can you make it the day before?

Yes

The soup base can be made entirely the day before and reheated. The bread and cheese are added at the last minute.

Reheating : How do you reheat it?

Reheat the soup base gently in a saucepan or in the microwave. For the gratin, pour the hot soup into bowls, add bread and Gruyère, then broil for 5-10 min in a 200°C oven or under the broiler until golden.

Variations

Alcohol-free version: replace the dry white wine with one tablespoon of apple cider vinegar mixed with extra broth.
Vegetarian version: substitute the beef broth with a robust vegetable broth made with white mushrooms to keep a nice roundness.
Swiss version: swap the shredded Gruyère for an equal mix of Emmental and raclette cheese for an even stretchier gratin.
For an extra touch of aroma, add a pinch of dried thyme or a bay leaf while the broth cooks.

Mistakes to avoid

Cooking the onions over too high a heat, which could blacken them and add an unpleasant bitterness to the broth.
Using fresh untoasted bread, which would fall apart instantly in the hot liquid instead of holding up the cheese.
Skipping the flour step (singeage), which lightly thickens the broth and prevents a watery liquid under the gratin.

Frequently asked questions

Which white wine should I choose for onion soup?

Go for a dry, crisp white wine such as a Sauvignon Blanc, an unoaked Chardonnay or a Muscadet. Avoid sweet or off-dry wines, which would upset the natural sweetness of the already softened onions.

Which cheese can I use instead of Gruyère?

Aged Comté, French Emmental or Beaufort all work perfectly. They melt easily and form a nicely golden crust while keeping a fruity flavor that pairs well with the hot broth.

How do I keep the bread from sinking to the bottom of the bowl?

Toast your country bread slices beforehand to dry them out thoroughly. They will float on top of the soup under the weight of the shredded cheese without sinking.

Can I replace the beef broth with chicken broth?

Yes, chicken broth works very well. The result will be slightly lighter in color and milder in taste, but just as flavorful and comforting.