Go Back
–+ servings
melted cheese on top of a bowl full of onion soup
Print Recipe
4.62 from 13 votes

Slow Cooker Caramelized French Onion Soup

Slow cooker caramelized French onion soup is an easy, restaurant-level dish that will disappear as fast as you serve it. Use your crockpot to first caramelize the onions, then add soup ingredients right in for a finished dish that is a home run - every time!
Prep Time20 minutes
Cook Time12 hours
add soup ingredients and continue to cook on low4 hours
Total Time16 hours 20 minutes
Course: Brunch, dinner, lunch, Soup
Cuisine: French
Keyword: Caramelized onion soup, Crockpot French onion soup, slow cooker onion soup
Servings: 6 servings
Calories: 196kcal
Author: The Lazy slow cooker

Equipment

Ingredients

Caramelized onions

  • 3 lbs onions I use yellow
  • 3 tablespoon olive oil can substitute with butter

Soup

  • 8 cups of beef broth can substitute with onion or vegetable broth
  • ½ cup cooking sherry
  • 1 tablespoon garlic minced
  • 1 tablespoon Worcestershire sauce
  • ¼ teaspoon Thyme dried
  • small French bread sliced and toasted
  • Gruyere cheese sliced or grated

Instructions

How to use your slow cooker to caramelize onions

  • quarter and then slice onions and break apart nested pieces
    3 lbs onions
  • place onions pieces and olive oil into slow cooker and stir to coat
    3 lbs onions, 3 tablespoon olive oil
  • cover and cook on low for 12-14 hours (It is great to do this overnight)
  • IMPORTANT NOTE: If you prefer, you can caramelize the onions on a cooktop in a more traditional format. However you do it, Do not skip this step! This soup will not turn out without caramelizing the onions first!

How to make onion soup

  • add all ingredients but bread and cheese into slow cooker
    3 lbs onions, 8 cups of beef broth, ½ cup cooking sherry, 1 tablespoon garlic, 1 tablespoon Worcestershire sauce, ¼ teaspoon Thyme
  • cover and cook on low for 4-6 hours
  • when ready to serve, place soup into individual bowls
  • place a piece of toasted French bread onto of soup and cover with cheese
    small French bread, Gruyere cheese
  • place bowl under broiler for 5 minutes until cheese is melted and bubbling

Notes

Notes
Nutritional calculation does not include French bread or cheese topping
Substitution suggestion:  Provolone cheese and swiss cheese are both great in place of Gruyere.  
Onions MUST be caramelized before making soup.  
Caramelized onions are great in other dishes too.  If you plan to use them to top other dishes, cook for the last hour or so with the lid off to allow some of the liquid to evaporate

Nutrition

Calories: 196kcal | Carbohydrates: 23g | Protein: 6g | Fat: 8g | Saturated Fat: 1g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 5g | Sodium: 1229mg | Potassium: 547mg | Fiber: 4g | Sugar: 10g | Vitamin A: 11IU | Vitamin C: 18mg | Calcium: 79mg | Iron: 1mg