What is French onion soup gratinée?
At its simplest, French onion soup gratinée is caramelized onions simmered in a rich stock, then baked until bubbling under slices of bread and Gruyère. More elaborate versions call for consommé—a fully clarified, crystal-clear stock. It takes a fair bit of work and, honestly, unless you’re serving the soup for a special occasion, it’s not really necessary. Better to focus your energy on what matters most: flavor.
And hey, time is money: save time on the stock, and you’ll have more to spend on a mountain of Gruyère for the occasion. Hehe.
The origins of French onion soup
As with many classic French recipes, there are plenty of legends. That said, my favorite is the tale of a French monarch in his hunting lodge realizing he only had onions, butter, and champagne on hand, then using them to invent onion soup. I don’t think an anecdote can get much more French than that. The fact that the soup later became popular among “the common folk” for its ability to mask the smell of alcohol after a drinking binge is the icing on the cake.
Ingredients
Stock
- beef bones, chicken carcass, or turkey carcass
- 1 onion
- 3 cloves garlic, peeled
- 1 sprig of thyme
Caramelized Onions
- 800 g onions, thinly sliced
- 2 tablespoons butter
- 2 teaspoons sugar
Soup
- 1 baguette sliced and lightly toasted
- 1 package grated Gruyère
Instructions
Stock
- In a large pot, cover the bones or carcass with water and boil for 10 minutes.
- Drain off the water, along with any impurities floating in it, then refill the pot with cold water.
- Simmer with the vegetables for 2-3 hours.
- Strain and set aside.
Caramelized Onions
- In a large pot, ideally heavy-bottomed, caramelize the onions with the butter and sugar over low heat for about 30 minutes, stirring occasionally, until evenly deep golden brown.
- Optional: deglaze with white wine.
Soup
- Pour about 2 L of the stock into the pot with the onions and simmer over low heat for 20 minutes.
- Transfer the soup to ovenproof bowls.
- Arrange the toasted bread on top.
- Sprinkle generously with grated Gruyère.
- Bake in a 230-degree oven until the cheese is melted and golden.
Nutrition
Tips for making great French onion soup
- Use a robust stock: this may be subjective, but for this soup I prefer a very meaty stock—beef stock, in other words. It pairs beautifully with the flavor of Gruyère.
- Don’t skimp on caramelizing the onions: the more caramelized, the better. If it takes more than 30 minutes to get that deep, beautiful color, so be it. Believe me, it’s worth it.
If you’d like to step away from French cooking while still enjoying a delicious broth, have you seen my chicken paella recipe?
