My momma use to make french onion soup every now and again and my mouth would be watering while I’ll smelled it cooking for few hours on the stove top.  This is an easy way to get that same comfy feeling right from your crock pot, although I do have to say making sure you have a good baguette to top  your cup of soup along with a fresh cheese so that everything melts and browns perfectly on top 😉 

French Onion Soup in Slow-Cooker

  • 3 pounds yellow onions, peeled, cut in half and thinly sliced
  • 2 tablespoons unsalted butter, melted
  • 2 tablespoons olive oil
  • 2 ½ teaspoons kosher salt
  • ½ teaspoon freshly ground black pepper, or more to taste
  • 2 sprigs fresh thyme
  • ¼ cup balsamic vinegar
  • 8 cups (2 32-ounce cartons) beef broth
  • ⅓ cup brandy, optional but recommended
  • 4 to 6 baguette slices, toasted (1 slice per bowl)
  • 1 ⅓ to 2 cups grated Gruyere cheese (⅓ cup per bowl)


  1. Put the onion slices in a 5-quart (or larger) slow cooker, along with the butter, olive oil, salt, and black pepper.
  2. Cover the crockpot and cook on low overnight, or for 10-12 hours. The onions should be dark golden brown and soft.
  3. Add the beef broth, balsamic vinegar, and fresh thyme.
  4. Cover and continue cooking on low for 6 to 8 hours.
  5. Season to taste with additional salt and pepper, if desired, and stir in the brandy, if using.
  6. Preheat the oven to 350 degrees Fahrenheit (180 degrees Celsius).
  7. In evenly-portioned amounts, ladle the soup into oven-safe bowls. Place the bowls on a baking sheet to catch any spills while in the oven.
  8. Top each bowl with a baguette slice and the shredded Gruyere.
  9. Bake for 10 to 15 minutes, until the cheese is completely melted.
  10. Turn the oven to broil and brown the tops for 2 to 3 minutes, or until the cheese is bubbling and browned. Remove from the oven and let cool for a few minutes before enjoying!