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Crockpot French Onion Soup Recipe
Ben Carraoli

Crockpot French Onion Soup Recipe

I have to admit, I’ve fallen in love with this Crockpot French Onion Soup. There’s something magical about walking into the kitchen and smelling those sweet, caramelized onions mingling with a rich, savory broth. Every time I make it, I can’t wait to pile on the bread and gooey cheese and dig in. It’s comforting, satisfying, and honestly, it feels a bit fancy even on a regular weeknight
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Total Time 6 hours 20 minutes
Servings: 8
Ingredients Method Notes

Ingredients
  

  • 3 large white onions thinly sliced – they caramelize beautifully without being overly sweet.
  • 3 tablespoons unsalted butter – gives the onions a rich creamy flavor as they cook.
  • 64 ounces beef broth preferably reduced sodium – makes the soup hearty without being too salty.
  • 1 tablespoon Worcestershire sauce – adds a subtle depth and umami to the broth.
  • 1 clove garlic minced – gives a gentle aromatic kick.
  • ⅓ cup dry sherry – enhances the flavor complexity and balances the sweetness of the onions.
  • 4 sprigs fresh thyme – fresh herbs always outperform dried here for brightness and fragrance.
  • Salt and pepper to taste – season slowly, adjusting as the soup reduces.
  • Baguette slices – for topping preferably a day or two old for sturdier bread.
  • 2 cups Gruyere cheese shredded – melts beautifully and creates that iconic cheesy crust.

Method
 

  1. I start by slicing the onions thinly so they cook evenly. Next, I melt butter in the slow cooker and add the onions, stirring to coat them. Sprinkle with a little salt to draw out moisture and enhance natural sweetness.
  2. Cook the onions on low for 6 hours, stirring occasionally. I love how the slow cooker allows them to caramelize gradually, giving the soup that rich, sweet flavor. Patience here is key—rushing caramelization changes the flavor entirely.
  3. Once the onions are golden and soft, I pour in the beef broth, Worcestershire sauce, garlic, dry sherry, and fresh thyme. Stir everything together and let it simmer on low for about an hour. This step really lets the flavors meld beautifully.
  4. While the soup simmers, I slice the baguette and shred the Gruyere. I like to toast the bread lightly before topping it with cheese—this prevents it from becoming too soggy when broiled.
  5. I ladle the soup into oven-safe bowls, place a slice of bread on top, and sprinkle generously with Gruyere. Then, I pop the bowls under the broiler until the cheese is bubbly and golden. Watching it melt is always my favorite part!

Notes

  • I always slice onions thinly and evenly so they caramelize uniformly.
  • Taste as you go—adjust salt and pepper after adding the broth for perfect seasoning.
  • Using dry sherry instead of cooking wine gives a richer, smoother flavor.
  • I like to broil the cheese just before serving to get that perfect golden crust.
  • Leftover caramelized onions can be frozen for future soups or casseroles.