Slow-Cooked French Onion Soup

Total Time

Prep: 30 min. Cook: 7 hours


8 servings (2 quarts)

Updated: Mar. 05, 2023
My husband and I love French onion soup, so I wondered if I could turn it into a less labor-intensive dish by altering my recipe to work in a slow cooker. The rich, cheesy result was an instant winner at home. —Ronda Eagle, Goose Creek, South Carolina
Slow-Cooked French Onion Soup Recipe photo by Taste of Home


  • 2 tablespoons butter, cubed
  • 2 large sweet onions, halved and thinly sliced
  • 1 large red onion, halved and thinly sliced
  • 1/2 teaspoon coarsely ground pepper
  • 2 cans (10-1/2 ounces each) condensed beef broth, undiluted
  • 3 cups water
  • 3/4 cup white wine or regular-strength beef broth
  • 2 fresh thyme sprigs
  • 1 fresh parsley sprig, optional
  • 1 bay leaf
  • 2 teaspoons Worcestershire sauce
  • 16 slices French bread (1/4 inch thick)
  • 3/4 cup shredded Gruyere or Swiss cheese


  1. Place butter in a 5-qt. slow cooker. Top with sweet and red onions; sprinkle with pepper. Cook, covered, on low until onions are tender, 5-6 hours.
  2. Stir in broth, water, wine, herbs and Worcestershire sauce. Cook, covered, on low until flavors are blended, 2-3 hours. Remove herb sprigs and bay leaf.
  3. To serve, preheat broiler. Place bread on a baking sheet; broil 4 in. from heat until lightly toasted, 1-2 minutes per side. Top bread with cheese; broil until cheese is melted, 1-2 minutes. Divide soup among eight bowls; top with cheese toasts and serve immediately.

Test Kitchen tips
  • Gruyere cheese is delicious in this recipe—its sweet, nutty flavor goes well with the oniony broth, and it melts wonderfully.
  • Toasting the bread with cheese separately, instead of broiling on top of the soup in crocks, prevents the underside of the bread from becoming soggy.
  • Nutrition Facts

    1 serving: 157 calories, 7g fat (4g saturated fat), 19mg cholesterol, 706mg sodium, 15g carbohydrate (6g sugars, 1g fiber), 7g protein.