Go Back
–+ servings
French Onion Soup

Comforting Slow Cooker French Onion Soup You'll Love

This delightful slow cooker French onion soup is filled with rich flavors and comforting aromas, making it a perfect dish for chilly evenings.
Print Recipe Pin Recipe
Prep Time 15 minutes
Cook Time 12 hours
Total Time 12 hours 15 minutes
Servings: 6 bowls
Course: APPETIZERS
Cuisine: French
Calories: 320
Ingredients Equipment Method Nutrition Notes

Ingredients
  

For the Soup
  • 3 lbs Yellow Onions Slice thinly for even cooking.
  • 2 tbsp Unsalted Butter Can be substituted with olive oil.
  • 2 tbsp Olive Oil Melted butter can also work as a substitute.
  • 2 tsp Kosher Salt Adjust according to preference.
  • Freshly Ground Black Pepper Add to taste.
  • 10 cups Reduced-Sodium Beef Broth Use vegetable broth for a vegetarian option.
  • 2 tbsp Balsamic Vinegar Optional but enriches the flavor.
  • 3 tbsp Brandy Optional, can be omitted.
For Topping
  • 4 to 6 slices Toasted Baguette Slices Stale bread works best for a crispy bite.
  • 1 1/3 to 2 cups Grated Gruyère Cheese Swiss cheese is a great alternative.

Equipment

  • slow cooker

Method
 

How to Make French Onion Soup
  1. Start by placing your sliced onions into a slow cooker. Mix in the unsalted butter, olive oil, kosher salt, and freshly ground black pepper to coat the onions evenly.
  2. Cover the slow cooker and set it on LOW. Let those onions cook for about 12 hours until they become a deep, dark golden brown and soft to the touch.
  3. Once the onions are caramelized, stir in the reduced-sodium beef broth and balsamic vinegar.
  4. Cover again and let it cook on LOW for an additional 6 to 8 hours, adjusting seasonings as necessary.
  5. When ready, ladle the soup into oven-safe bowls and place them on a rimmed baking sheet.
  6. Place the toasted baguette slices on top of each bowl, then generously sprinkle with grated Gruyère cheese.
  7. Preheat your oven to 350°F and bake for 20-30 minutes, until the cheese is melted and bubbly.
  8. For the finishing touch, broil each bowl for 2-3 minutes until the cheese is golden brown and bubbly.

Nutrition

Serving: 1bowlCalories: 320kcalCarbohydrates: 41gProtein: 10gFat: 13gSaturated Fat: 7gMonounsaturated Fat: 5gCholesterol: 30mgSodium: 860mgPotassium: 800mgFiber: 2gSugar: 5gVitamin A: 8IUVitamin C: 12mgCalcium: 15mgIron: 10mg

Notes

Garnish with fresh parsley for an elegant touch. Slice onions thinly for even cooking. Keep the slow cooker lid tightly sealed to retain moisture.

Tried this recipe?

Let us know how it was!