Makes 6 servings
The worst part of making classic French onion soup is chopping all the onions! Here’s the good news: You can indeed use frozen chopped onions. But you have to modify the standard technique, using some of them up front for flavor and then more toward the end for texture. In fact, consider this the rule for frozen chopped onions in all stews, soups, and braises: most up front, the rest toward the end. True, you don’t save much off the standard stovetop timing here. (Physics is physics. Caramelizing will always take time.) But the results are as good as the real thing, made easier by modern convenience.
6 tablespoons (¾ stick) unsalted butter
2 pounds frozen chopped onions (do not thaw)
3 tablespoons brandy
7 cups no-salt-added beef broth
2 teaspoons minced fresh sage leaves, optional
2 teaspoons fresh thyme leaves
½ teaspoon table salt
½ teaspoon ground black pepper
6 thick French bread slices, lightly toasted
2 cups shredded Gruyère (about 8 ounces)
1. Melt the butter in a Dutch oven set over high heat. Measure out ¾ cup frozen chopped onions and set aside at room temperature. Pour the remaining frozen onions into the Dutch oven and cook in the butter, stirring frequently as they reduce, until the onions thaw and any additional liquid boils away, about 10 minutes.
2. Reduce the heat to very low, cover, and cook, stirring frequently at first but then less so as the heat calms down, for 30 minutes.
3. Uncover the pot and continue cooking, stirring often, until the onions are a deep golden brown, about 1 hour.
4. Increase the heat to medium. Stir in the brandy and scrape up any browned bits in the pot as it comes to a boil. Add the broth, sage (if using), thyme, salt, and pepper.
5. Working over the sink, squeeze the remaining chopped onions dry in small handfuls to get rid of excess moisture, then stir them into the pot. Reduce the heat again to very low. Cover and simmer slowly for 1 hour.
6. Position the oven rack about 6 inches from the broiler element; heat the broiler. Divide the soup into six broiler-safe serving bowls, perhaps set on a large lipped baking sheet. Float a piece of bread in each bowl, then top the bread with about ⅓ cup cheese. Broil (watch carefully!) until the cheese melts and bubbles, about 2 minutes.