Jul 14 2026
Restaurants312 ChicagoFrench Onion Gratin Recipe

French Onion Gratin Recipe

Inspired by 312 Chicago
Time1h 30m
Serves4

Rich Vegetable & Stout Broth, Brioche Crouton, Gruyere

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Ingredients

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Broth

Method

Broth Preparation

  1. 1

    Sauté Onions

    In a large pot, heat the olive oil over medium heat. Add the sliced onions and cook, stirring occasionally, until they are caramelized and golden brown, about 25-30 minutes.

  2. 2

    Add Garlic

    Add the minced garlic to the pot and sauté for an additional 2-3 minutes until fragrant.

  3. 3

    Combine Broth Ingredients

    Pour in the vegetable broth and stout beer. Add the chopped thyme, bay leaf, salt, and pepper. Bring the mixture to a simmer.

  4. 4

    Simmer

    Reduce the heat to low and let the broth simmer for about 30 minutes, allowing the flavors to meld together.

Brioche Crouton Preparation

  1. 5

    Preheat Oven

    Preheat your oven to 375°F (190°C).

  2. 6

    Prepare Croutons

    In a large bowl, toss the brioche cubes with melted butter, garlic powder, and salt until evenly coated.

  3. 7

    Bake Croutons

    Spread the croutons in a single layer on a baking sheet. Bake in the preheated oven for 10-15 minutes or until they are golden and crispy, turning halfway through.

Assembling the Gratin

  1. 8

    Preheat Broiler

    Turn on the broiler setting in your oven.

  2. 9

    Combine Broth and Croutons

    Once the broth is ready, remove the bay leaf. Ladle the broth into oven-safe bowls and top with a generous amount of baked brioche croutons.

  3. 10

    Add Cheese

    Sprinkle the grated Gruyere cheese over the croutons in each bowl.

  4. 11

    Broil

    Place the bowls under the broiler for 3-5 minutes or until the cheese is bubbly and golden brown. Watch closely to avoid burning.

  5. 12

    Garnish and Serve

    Remove from the oven, garnish with chopped parsley, and serve immediately.