2 tablespoons unsalted butter
2 tablespoons extra-virgin olive oil
3 pounds yellow onions, cut into ¼-inch slices
2 cloves garlic, chopped
Freshly ground black pepper
2 tablespoons all-purpose flour
1 tablespoon Dijon mustard
3 cups dry white wine, or dry red wine
2 bay leaves
6 cups chicken stock, preferably homemade
¾ pound Gruyere or other Swiss-type cheese, grated
Six 1-inch slices of rustic country bread, toasted and buttered
Salt

This is the onion soup of onion soups. I seek out this rich soup in restaurants when I am in Paris, usually without much luck unless I go to a tourist restaurant. So when I arrive, I make my own. This recipe comes from Christopher Hirsheimer, the photographer for this book, and a great cook.

In a large, heavy pot melt the butter in the olive oil over medium high heat. Add the onions and garlic and reduce the heat to medium. Cook, stirring continuously, for about 20 minutes or until the onions are nice and brown. Season with pepper.

Add the flour, stirring it into the mixture so it cooks for a minute or two. Add the mustard and stir to incorporate.

Add the wine and the bay leaves and cook for about 5 minutes. Add the stock a little at the time, and simmer very slowly for at least 30 minutes. If the stock is evaporating too quickly, or if you have an extra guest at the last moment, add a cup or two of extra stock or water.

Just before serving, preheat the oven to broil. Mound about two-thirds of the cheese on the toast slices and place them on a baking sheet. Broil, watching very carefully, until the cheese is melted and lightly browned.

Ladle thesoup into warm soup bowls, add a tablespoon of cheese to each bowl for extra richness, and then float the cheese toast on top.

Serves 4 to 6

Tips for the Best Onion Soup

Do not salt the onions while they are browning; salt causes the onions to sweat water and they will not brown as nicely.

Make ahead: the soup and the broiled cheesy toasts can be made ahead of time and warmed and assembled at the last minute. Perfect for a late-night supper.