This crockpot French onion soup recipe is an easy take on an elegant classic without compromising on any of its rich and buttery goodness. It’s effortless and delicious comfort food, served with French bread and topped with melty cheese.

 

Easy Slow Cooker French Onion Soup

This crockpot French onion soup is an effortless version of the elegant French classic, full of rich and intense flavors. When all you have to do is throw everything into the pot and then let the soup cook itself, French cuisine might not seem so intimidating afterall.

With a deep caramelized flavor from slowly cooked onions and a hint of sweetness, this broth-based recipe has a complex flavor profile without making the steps to get there any harder. Don’t forget the thyme! Its aroma pairs beautifully with the soup’s buttery goodness.

Topped with a slice of French bread and lots of melty Gruyere cheese, this soup is an ode to French flavors. Easily made in the crockpot and frozen for future cravings, this recipe is the kind of pick-me-up soup your weeknights were missing.

Ingredients You’ll Need

This crockpot French onion soup is loaded with classic French ingredients like wine, thyme, and butter. Check the recipe card at the bottom of the post for full ingredient amounts. For more soup inspiration, go through my Creamy Tortellini Soup and Italian Wedding Soup recipes.

• Sweet onions – You can use yellow onions, but increase the sugar to 1 teaspoon.
• Unsalted butter – If you use salted butter, reduce the salt in the rest of the recipe.
• Sugar – Any kind of sugar (except powdered) will work.
• Salt and ground pepper
• Fresh thyme – Don’t skip this one. It’s super important for the soup’s signature taste.
• Bay leaf
• Low-sodium beef broth – This will make the richest soup, but chicken broth is a good alternative. For a vegetarian version, use veggie stock.
• Dry white wine – Don’t use any sweet wines.
• French bread
• Gruyere cheese – Feel free to use Swiss cheese instead.

How to Make Crockpot French Onion Soup

• Fill the crockpot. Place sliced onions in a 6-quart slow cooker. Stir in melted butter, sugar, salt, and pepper. Top with thyme and bay leaf.
• Cook it. Cover the crockpot with the lid and cook on LOW for about 8 hours, or until onions are browned and caramelized. Stir halfway through. 
• Add the broth. Once onions are caramelized, stir in the beef broth and wine. Taste for salt and pepper and season accordingly.
• Continue cooking. Cover again and cook on LOW for 4 hours, or on HIGH for 2 hours, or until heated through. Remove and discard thyme and bay leaf.
• Continue cooking. Cover again and cook on LOW for 4 hours, or on HIGH for 2 hours, or until heated through. Remove and discard thyme and bay leaf.
• Serve. Ladle soup into ovenproof bowls. Top the bowls with a slice of french bread and cheese. Broil in the oven until cheese is melted, about 2 to 3 minutes. Enjoy.

Tips for Success

Making crockpot French onion soup just got a whole lot easier with these tips.

• Use croutons. Don’t worry if you’re out of French bread, you can top it with your favorite croutons for the same texture.
• Start it on the stove to make a quicker version of crockpot French onion soup. Combine onions, butter, sugar, salt, and pepper in a large skillet, and cook the onions for about 25 minutes or until browned and caramelized. Transfer the onions to the slow cooker, add beef broth, wine, thyme, salt, and pepper, and cook for 6 hours on LOW. When the soup is ready, ladle it into ovenproof bowls, place a slice of baguette in each bowl, top with shredded cheese, and broil for a couple of minutes or until the cheese is melted.
• Watch the onions. There’s a fine line between golden, caramelized onions and burned onions. Keep an eye on the pan and remove it from the heat once the onions have caramelized, otherwise, your soup will taste bitter.

Serving Suggestions

This crockpot French onion soup is the perfect starter for all your fancy (but easy) meals. I love to serve it with my Easy Rib Eye Steak Dinner or Grilled Scallops as main dishes. Paired with Fluffy Couscous with Asparagus and Golden Raisins and Caponata, it’s the ultimate show-stopping dinner.

How to Store & Reheat Homemade French Onion Soup

• Once fully cooled, refrigerate the soup in an airtight container for up to 4 days.
• To reheat it, pop it into the microwave for 1-2 minutes or until warm. You can also heat it in a pot over medium heat for 5-7 minutes.
• To Freeze: Transfer the soup in serving-size portions in freezer-friendly bags or containers. Freeze the soup for up to 3 months. Let it thaw in the fridge overnight a day before serving. Reheat it as usual.

More Soup Recipes to Try

• Slow Cooker Creamy Cauliflower Soup
• Slow Cooker Vegetable Soup
• Slow Cooker Vichyssoise Soup (Leek and Potato Soup)
• Crock Pot Chicken Enchilada Soup
• Crock Pot Lemon Rice Soup

ENJOY!