Crockpot French Onion Soup

Two white mugs filled with French onion soup, topped with toasted bread and melted cheese, on a rustic tray.

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Crockpot French onion soup with caramelized onions, rich broth, toasted bread and melted cheese just like traditional French onion soup, done easy and hands free in the slow cooker!

Prep: 25

Cook: 7 30

Total: 8

Servings: servings

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Ingredients

2 tablespoons unsalted butter melted
3 pounds yellow onions thinly sliced (6 medium onions)
4 garlic cloves minced (about 4 teaspoons)
1 tablespoon fresh thyme leaves or 1 teaspoon dried thyme
1 ½ teaspoons kosher salt plus additional to taste
¼ teaspoon ground black pepper
4 cups low-sodium beef broth (1 quart)
½ cup dry white wine such as Sauvignon Blanc
8-12 slices French bread 1/4-inch thick
3 tablespoons extra-virgin olive oil
½ cup shredded Gruyere cheese

Instructions

In a 6-quart slow cooker, combine the butter, onions, garlic, thyme, salt and pepper. Cover and cook on high for 5 to 7 hours, stirring occasionally, until the onions are caramelized.
Stir in the broth and wine. Cover and cook on high for 30 additional minutes.
Meanwhile, place a rack in the upper third position of the oven (about 6 inches from the top) and preheat the broiler. Arrange the bread slices on a baking sheet. Brush both sides with the oil and place under the broiler for 2 to 3 minutes per side, keeping a close eye on them and rotating the pan to avoid burning. Remove from the oven.
When the soup is done, divide it between 4 oven-safe bowls or ramekins. Place 2 or 3 baguette slices on top of each ramekin and sprinkle about 2 tablespoons of cheese on top of each.
Place the bowls on a baking sheet and broil for about 2 minutes, until browned and bubbling, keeping a close eye on them under the broiler. Sprinkle with a pinch of salt and pepper and serve.

Notes

SUBSTITUTION NOTES: I don’t really recommend substitutions, but in a pinch, you could use chicken or vegetable broth (veggie broth would be fine for vegetarians). Swiss cheese or Emmental would work (but gruyere is the best!)
TO STORE: Refrigerate leftover soup (without the toppings) in an airtight storage container for up to 4 days. Store bread separately in an airtight storage container at room temperature.
TO REHEAT: Rewarm leftovers in a pot on the stovetop over medium-low heat or in the microwave. Then, top with the toasted bread and cheese and broil as directed in the recipe.
TO FREEZE: Freeze soup in an airtight, freezer-safe storage container for up to 6 months. Let thaw overnight in the refrigerator before reheating.

Nutrition

Serving: 1(of 4)Calories: 593kcalCarbohydrates: 80gProtein: 21gFat: 20gSaturated Fat: 7gPolyunsaturated Fat: 2gMonounsaturated Fat: 9gTrans Fat: 0.2gCholesterol: 27mgSodium: 1774mgPotassium: 950mgFiber: 7gSugar: 17gVitamin A: 338IUVitamin C: 23mgCalcium: 264mgIron: 5mg