Fans of French onion soup who love it for its caramelized onions, beefy broth and cheesy toast topping won't be disappointed with this recipe, which offers all those elements plus a hands-on time of only 20 minutes.
Nutrition per serving may change if servings are adjusted.
10 cups vertically sliced onions (from 5 onions)
2 tablespoons unsalted butter, melted
½ teaspoon black pepper
6 cups unsalted beef stock
¼ cup dry Marsala wine
1 teaspoon chopped fresh thyme, plus more for garnish
¾ teaspoon kosher salt
12 ounces whole-wheat baguette (see Tip), cut into 16 slices
5 ounces Gruyère cheese, shredded (about 1¼ cups)
Coat a 4-quart slow cooker with cooking spray. Stir together the onions, butter and pepper in the slow cooker; cover and cook on LOW until the onions are very soft and deep golden brown, about 10 hours.
Stir in the stock, marsala, thyme and salt. Cover and cook on HIGH until the flavors are blended, about 2 hours.
Preheat the broiler with the oven rack 6 inches from the heat. Place the baguette slices on a baking sheet, and sprinkle evenly with the Gruyère. Broil until the Gruyère melts, 2 to 3 minutes. Ladle the soup into bowls. Top with the cheese toasts. Garnish with the additional thyme, if desired.
Tip: The Gruyère toasts are a smart, tasty application for bread that's beginning to pass its prime. If you have enough day-old bread on hand, don't bother with purchasing a fresh loaf. Toasting it cancels out any differences in flavor that it has from fresh bread.