The onion soup originates from the French cookbook “Gastronomie Pratique,” which was written in 1907 by Henri Babinski. The Times published the recipe in 1974, when the book was first translated into English.

It is a strange recipe for soup that yields delicious results. Baguette toasts are spread with butter and layered with grated cheese, sautéed onions and tomato purée. Then, in what seems to be a nod to stone soup, salted water is gently poured in. The dish is then simmered and baked, and by the time it is done, the “soup” is like a savory bread pudding and the top has a thick, golden crust that your guests will fight to the death over.

Ingredients

  • 1 baguette, cut into 1/2-inch slices (about 25 to 30)
  • 9 tablespoons butter, softened
  • 9 ounces Emmental cheese, finely grated
  • 8 medium yellow onions, thinly sliced (about 12 cups)
  • 1 tablespoon kosher salt, more to taste
  • 1 cup tomato purée
  • Nutritional Information
    • Nutritional analysis per serving (6 servings)

      565 calories; 33 grams fat; 19 grams saturated fat; 1 gram trans fat; 8 grams monounsaturated fat; 1 gram polyunsaturated fat; 50 grams carbohydrates; 5 grams dietary fiber; 13 grams sugars; 18 grams protein; 89 milligrams cholesterol; 1819 milligrams sodium

    • Note: Nutrient information is not available for all ingredients. Amount is based on available data.

Serves 6

Preparation

  1. Toast the baguette slices and let them cool. Spread a generous layer of butter on each slice (you will need about 5 tablespoons), then lay the slices close together on a baking sheet and top with all but 1/2 cup of cheese.
  2. In a large saucepan, melt the remaining 4 tablespoons butter over medium heat. Add the onions, season with salt and sauté, stirring occasionally, until very soft and golden, about 15 minutes.
  3. In a 5-quart casserole, arrange a layer of bread slices (about 1/3 of them). Spread 1/3 of the onions on top, followed by 1/3 of the tomato purée. Repeat for two more layers. Sprinkle with the remaining 1/2 cup cheese. To avoid boiling over, the casserole must not be more than 2/3 full.
  4. In a saucepan, bring 1 1/2 quarts water to a boil. Add the salt. Very slowly pour the salted water into the casserole, near the edge, so that the liquid rises just to the top layer of cheese without covering it. (Depending on the size of your casserole, you may need more or less water.)
  5. Preheat the oven to 350 degrees. Put the casserole on the stove and simmer uncovered for 30 minutes, then transfer to the oven and bake uncovered for 1 hour. The soup is ready when the surface looks like a crusty, golden cake and the inside is unctuous and so well blended that it is impossible to discern either cheese or onion. Each person is served some of the baked crust and some of the inside, which should be thick but not completely without liquid.

2 hours 15 minutes

Dining and Cooking