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Slow Cooker French Onion Soup

Letting these ingredients marinate together in the slow cooker adds so much flavor to this comforting classic!

We still marvel at how some recipes with the simplest ingredients can taste so amazing, and French onion soup is no exception. This soup has such rich flavor thanks to it’s main ingredients (beef broth and onions) and it’s low and slow cooking method – we even enlisted the help of our slow cooker for this particular version to make it that much easier. We finish ours off the traditional way, topped with a slice of bread and melted cheese, making it one of our all time favorite comfort foods that warms us up from the inside out!

Serves 8

30 minutes active; 4 hours inactive

Rated 5 out of 5
Rated by 8 reviewers
  • 4 pounds yellow onions, peeled and chopped
  • 10 cups beef broth
  • 1 baguette, sliced diagonally and toasted
  • 1 bay leaf
  • 1 1/2 cups Gruyere or swiss cheese, grated or sliced
  • 1/2 cup (1 stick) unsalted butter, melted
  • 1/4 cup all-purpose flour
  • 2 tablespoons extra-virgin olive oil
  • 2 tablespoons balsamic vinegar
  • 1 tablespoon Worcestershire sauce
  • kosher salt and freshly ground pepper, to taste
  • Minced chives, for garnish
  1. Place chopped onions, butter, and olive oil in a large skillet or pot, and cook over medium heat for 10-15 minutes, or until onions start to caramelize.
  2. In a small bowl, whisk flour into balsamic vinegar and Worcestershire sauce and mix until smooth.
  3. Transfer onions to slow cooker. Pour in beef broth, bay leaf, salt, pepper, and flour mixture, and stir well to combine.
  4. Cover and cook on low for 6-8 hours, or on high for 3-4 hours.
  5. Ladle soup into oven proof bowls, top each with 1 slice of bread and cheese, and broil, about 5 minutes or until cheese is melted and bubbly.
  6. Garnish with chives, serve hot and enjoy!

Recipe adapted from The Kitchn

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