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Soup • French

Slow Cooker French Onion Soup Recipe

Bistro-style French Onion Soup made easy in the slow cooker! You'll love how simple it is to make while you spoon up bites of sweet and savory onion, rich beef broth, hearty bread and gooey melted cheese.

4.8 from 154 votes
1090 mins
Total Time
8
servings
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Slow Cooker French Onion Soup

How to Make the Best Slow Cooker French Onion Soup

French onion soup is a classic bistro dish that seems intimidating to make, but this slow cooker version takes all the guesswork out while delivering authentic, restaurant-quality results. The secret lies in the slow caramelization of the onions—a process that typically takes hours on the stovetop but becomes effortless in the slow cooker.

This hearty, comfort-food soup is loaded with caramelized sweet onions, rich beef broth, and finished with a crusty bread slice topped with melted Gruyere cheese. It’s the kind of soup that warms you from the inside out, perfect for chilly days or when you want something special without spending all day in the kitchen. The long, slow cooking transforms ordinary onions into something truly magical.

The beauty of making this in a slow cooker is that you can set it and forget it, freeing up your time while the oven does the work. When dinner time rolls around, simply broil the bread and cheese on top for that signature golden, bubbly finish that makes French onion soup so irresistible.

Slow Cooker French Onion Soup

Slow Cooker French Onion Soup

Bistro-style French Onion Soup made easy in the slow cooker! You'll love how simple it is to make while you spoon up bites of sweet and savory onion, rich beef broth, hearty bread and gooey melted cheese.

4.8 from 154 votes
CourseSoup
CuisineFrench
Keywordcrock pot french onion soup, french onion soup, slow cooker french onion soup
Prep Time10 mins
Cook Time1080 mins
Total Time1090 mins
Servings8 servings
Calories426kcal
AuthorRare Ivy
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Ingredients

Main Ingredients

Toppings

Instructions

Caramelize the Onions

  1. Slice the onions into thin half-moon slices.
  2. In the slow cooker, combine the onions, butter, olive oil, and salt.
  3. Cook on low for 10 to 12 hours.

Make the Soup

  1. Once the onions have cooked down, add the brandy, beef broth, fresh thyme, bay leaves, and garlic.
  2. Cook on low for 8 hours or high for 4 hours.
  3. Season with salt and black pepper to taste.

Toast and Broil

  1. Just before the soup is done cooking, slice the bread into 2 to 4 inch wide slices, and grate the cheese.
  2. Toast the bread until golden brown.
  3. Ladle the soup into oven-safe bowls, top with toast and grated cheese.
  4. Set all the bowls on a sheet tray and broil on high for 3 to 5 minutes until the cheese is melted and starting to brown.
  5. Serve immediately.

Notes

  • This soup is perfect for slow cooker meal prep—the long, gentle cooking brings out the natural sweetness of the onions.
  • For extra depth of flavor, use a combination of different onion types like yellow, sweet, and white onions.
  • The soup can be made a day ahead and reheated before broiling with the bread and cheese.
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