Slow-Cooker French Onion Soup


In this genius slow-cooker soup recipe, two types of onions are caramelized for hours before adding a sherry-spiked broth. For a bistro-worthy presentation, ladle the soup into ovenproof crocks, top with the bread and cheese and broil.

Cook Time:
30 mins
Additional Time:
8 hrs
Total Time:
8 hrs 30 mins
8 servings



  • 2 tablespoons butter, cut into 8 pieces

  • 2 tablespoons extra-virgin olive oil

  • 8 sprigs fresh thyme

  • 4 cloves garlic, smashed

  • 1 bay leaf

  • 2 pounds yellow onions, halved and sliced (see Tip)

  • 2 pounds red onions, halved and sliced

  • 1 teaspoon salt

  • ¾ teaspoon ground pepper

  • 4 cups low-sodium beef broth

  • ¼ cup dry sherry

Cheese Toasts

  • 8 diagonal slices baguette (1/2-inch-thick), toasted

  • 1 cup shredded Gruyère or Swiss cheese


  1. To prepare soup: Scatter butter in a 6- to 7-quart slow cooker (see Tip). Add oil, thyme, garlic and bay leaf, then onions. Sprinkle with salt and pepper. Cover and cook on High for 8 hours.

  2. Bring broth and sherry to a boil in a saucepan. Remove the thyme sprigs and bay leaf from the slow cooker. Pour in the broth and cook on High, uncovered, for 10 minutes.

  3. To prepare cheese toasts: Meanwhile, position rack in upper third of oven; preheat broiler to high. Top each baguette slice with 2 tablespoons cheese. Broil until the cheese is melted, 1 to 2 minutes. Divide the soup among 8 bowls. Top each with a cheese toast.


Tips: Take the tears out of onion prep: Refrigerate whole, unpeeled onions for about 30 minutes before slicing or chopping. The cold “chills out” the sulfur compounds that can irritate your eyes and make you cry.

For easy cleanup, try a slow-cooker liner. These heat-resistant, disposable liners fit neatly inside the insert and help prevent food from sticking to the bottom and sides of your slow cooker.

To make ahead: Refrigerate soup (Steps 1-2) for up to 5 days or freeze for up to 3 months. Make cheese toasts before serving.

Equipment: 6- to 7-quart slow cooker

Nutrition Facts (per serving)

271 Calories
12g Fat
31g Carbs
12g Protein
Nutrition Facts
Servings Per Recipe 8
Serving Size 1 cup soup & 1 cheese toast
Calories 271
% Daily Value *
Total Carbohydrate 31g 11%
Dietary Fiber 5g 19%
Total Sugars 9g
Protein 12g 23%
Total Fat 12g 15%
Saturated Fat 5g 26%
Cholesterol 23mg 8%
Vitamin A 222IU 4%
Vitamin C 16mg 17%
Folate 40mcg 10%
Sodium 529mg 23%
Calcium 194mg 15%
Iron 1mg 4%
Magnesium 28mg 7%
Potassium 429mg 9%

Nutrition information is calculated by a registered dietitian using an ingredient database but should be considered an estimate.

* Daily Values (DVs) are the recommended amounts of nutrients to consume each day. Percent Daily Value (%DV) found on nutrition labels tells you how much a serving of a particular food or recipe contributes to each of those total recommended amounts. Per the Food and Drug Administration (FDA), the daily value is based on a standard 2,000 calorie diet. Depending on your calorie needs or if you have a health condition, you may need more or less of particular nutrients. (For example, it’s recommended that people following a heart-healthy diet eat less sodium on a daily basis compared to those following a standard diet.)

(-) Information is not currently available for this nutrient. If you are following a special diet for medical reasons, be sure to consult with your primary care provider or a registered dietitian to better understand your personal nutrition needs.

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