Mastering the Art of French Cooking: Soupe à l’Oignon Gratinée (Onion Soup Gratinéed with Cheese)

I was really excited to try this recipe. Who wouldn't be? French onion soup is everywhere, most of it bad, so I wanted to try the authentic article.  I did veer away from Julia's recipe in just one respect. When making the bread and cheese crouton toppers for the individual soups, I used Gruyére cheese instead of Swiss or Parmesan. I seem to remember reading somewhere that it's really good on onion soup, and plus, doesn't it still count as a Swiss cheese?

The result of my efforts was an incredibly rich and hearty soup, perfect for a winter's day. The onion were sweet, and the beef broth (yes, I used canned!) had picked up all the flavors, including the liquors. I was very impressed, and I think I'm ruined for this soup anywhere else.

Soupe à l’Oignon Gratinée (Onion Soup Gratinéed with Cheese)
Adapted from Mastering the Art of French Cooking by Julia Child, Louisette Bertholle, and Simone Beck

1½ pounds or about 5 cups of thinly sliced yellow onions
3 tablespoons unsalted butter
1 tablespoon oil
1 teaspoon sea salt
¼ teaspoon granulated sugar (helps the onions brown)
3 tablespoons all-purpose flour
2 quarts boiling brown stock, canned beef bouillon, or 1 quart of boiling water and 1 quart of stock or bouillon
½ cup dry white wine or dry white vermouth
Sea salt and freshly ground black pepper, to taste
3 tablespoons cognac
Rounds of hard-toasted French bread
1½ cups grated Swiss, or Swiss and Parmesan cheese
1 tablespoon olive oil or melted butter

Cook the onions slowly with the butter and oil in a covered 4-quart saucepan for 15 minutes.  Uncover, raise heat to moderate, and stir in the salt and sugar.  Cook for 30 to 40 minutes stirring frequently, until the onions have turned an even, deep, golden brown.  Sprinkle in the flour and stir for 3 minutes.

Off heat, blend in the boiling liquid.  Add the wine, and season to taste.  Simmer partially covered for 30 to 40 minutes or more, skimming occasionally.  Correct seasoning.

Just before serving, stir in the cognac.  Preheat oven to 325°F.

Bring the soup to the boil and pour into soup pots.  Float the rounds of toast on top of the soup, and spread the grated cheese over it.  Sprinkle with the oil or butter.  Bake for 20 minutes in the oven, then set for a minute or two under a preheated broiler to brown the top slightly.  Serve immediately.

Makes 6 to 8 servings