Slow Cooker French Onion Soup
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Experience a gourmet-style meal at home with this slow cooker French onion soup. Caramelized onions, garlic, herbs, and spices are slow-cooked in white wine and flavorful broth to create a cozy and comforting soup for everyone to enjoy. Serve with baguette slices topped with melted Gruyère and you’ve got a meal that feels straight out of a fancy restaurant!
Soup is my ultimate comfort food. Among my go-tos are pumpkin soup and avocado bone broth soup, but when I’m entertaining, I whip up my personal favorite – slow cooker French onion soup. It’s surprisingly easy to make for a dish that looks and tastes fancy. I love how it delivers rich, complex flavors that you simply can’t get from instant soups.
Enjoy this crave-worthy dish as an appetizer or side for family meals, as a starter at a dinner party, or anytime you crave a warm, hearty meal. Make it today and experience the magic of homemade French onion soup!
Table of Contents (click to view)
Why You’ll Love This Recipe
- Easy recipe: Enjoy a restaurant-worthy dish at home with minimal effort. Prep for 15 minutes and leave the rest to your slow cooker.
- Budget-friendly ingredients: This recipe requires affordable staples that deliver big flavor. No special grocery runs needed!
- Crave-worthy flavor: The rich, savory combination of caramelized onions, broth, white wine, herbs, and seasonings makes every bite crave-worthy.
- Cozy and comforting: French onion soup is a classic for a reason – it’s timeless, comforting, and always delivers that warm, cozy feeling we all crave.
- Customizable: Go as light or as loaded as you want with this dish. Choose a lighter soup base or substitute the white wine with a non-alcoholic alternative – make it how you want it!
- Great for any occasion: This soup is easy enough for weeknight meals and casual gatherings, but special enough for holidays and other special occasions.
How to Make Slow Cooker French Onion Soup
Any soup lover needs this recipe in their life. Slow cooker French onion soup is a restaurant-quality dish with casual weeknight simplicity and ease. Simply caramelize the onions, throw them in the pot with the broth and seasonings, garnish, and serve. Take the extra step to make cheesy baguette slices for the perfect cozy meal.
Scroll to the bottom of this post for a printable recipe card with a full list of ingredients, measurements, and step-by-step instructions.
Ingredients You Need
- Yellow onions: The key ingredient of this soup. They provide sweetness when caramelized and add a rich, savory depth to the broth. Avoid red onions, as they’re spicier and can alter the soup’s color.
- Butter and olive oil: Essential for caramelizing the onions to a deep golden color and enhancing their flavor.
- Garlic cloves
- Dry white wine: Used to deglaze the pan and cut through the richness of the soup for a balanced flavor.
- Beef broth
- Bay leaves, dried thyme, salt, and ground black pepper
- Baguette: Regular, gluten-free, or low-carb.
- Gruyère cheese: Melted on top of the baguette slices for a cheesy, golden finish that complements the soup perfectly. Grate it fresh for the best melt!
Step-By-Step Instructions
The biggest challenge with this recipe is waiting for the soup to cook because it smells amazing! I cook slow cooker French onion soup early in the afternoon and it’s ready just in time for dinner. It takes only 5 simple steps to make this incredible meal – follow the instructions below and I guarantee that your soup will come out perfect every time!
Step 1: Caramelize the onions
In a skillet, melt the butter with olive oil over medium heat. Add the sliced onions and cook, stirring frequently, for about 10-15 minutes until they soften and start to caramelize. Add the garlic during the last minute of cooking.
You can skip this step for a more hands-off approach, but caramelizing adds depth to the soup and I highly recommend it.
Step 2: Add the other ingredients
Transfer the onions (caramelized or raw) to the slow cooker. Add the white wine, beef broth, bay leaves, thyme, salt, and pepper. Stir to combine.
Step 3: Slow cook
Cook on HIGH for 4 to 6 hours or LOW for 6-8 hours. If skipping the caramelization step, extend the slow cooker time by 1 to 2 hours for deeper onion flavor.
Step 4: Prepare the baguettes
With about 10 minutes left in the cooking time, preheat the oven broiler. Place the baguette slices on a baking sheet, sprinkle with grated Gruyère, and broil for 2-3 minutes until bubbly and golden brown. Watch carefully to avoid burning.
Step 5: Garnish and serve
Remove the bay leaves from the soup. Ladle the soup into bowls and top with a cheesy baguette slice. Serve immediately. For extra richness, you can stir in a splash of cream or a pat of butter before serving.
Substitutions
While this recipe calls for ingredients you might already have in your kitchen, you may be missing some or prefer to use alternative ingredients. Here are my ingredient substitution ideas:
- Yellow onions: If you don’t have yellow onions, white onions work well as a substitute for their mild and sweet flavor.
- Butter and olive oil: You can replace these with vegan butter, avocado oil, or just stick with olive oil if you’re avoiding dairy.
- Garlic cloves: If you’re out of fresh garlic, substitute with garlic powder (1/8 tsp per clove) or use shallots for a milder taste.
- Dry white wine: No white wine? Try dry sherry, or for a non-alcoholic option, vegetable broth will work just fine.
- Beef broth: For a lighter version of the soup, swap beef broth with chicken or vegetable broth.
- Herbs: Use dried basil or thyme in place of bay leaves, and fresh thyme or oregano instead of dried thyme.
- Baguette: If you don’t have a baguette, any crusty bread like French bread, sourdough, or ciabatta will do the trick. Simply swap in your preferred low-carb alternative if you want to keep it gluten or grain-free.
- Gruyère cheese: If Gruyère isn’t available, you can use Swiss cheese, fontina, or sharp cheddar for a similar melt and flavor.
Expert Tips
- Use quality broth: The broth is the base of the soup, so use high-quality beef or chicken broth for the best flavor. Learn how to make your own beef bone broth at home to make sure you’re using a rich, flavorful, and quality soup base.
- Skip the bread: If bread doesn’t fit your diet, just sprinkle the cheese over the broth and let it melt. The cheesy onion soup is still just as delicious.
- Check the saltiness: Most broths and cheeses are already salty, so I recommend tasting your soup before adding salt to avoid over-seasoning.
- Make it ahead: This soup gets even better the next day, so consider making it ahead of time and reheating it for a more developed flavor. Just store it in the fridge and reheat when you’re ready to enjoy.
How to Store This Recipe
Let the soup cool completely, then transfer it to an airtight container. Store it in the fridge for up to 2 days or freeze it for up to 1 month. When ready to serve, gently warm the soup on the stove and toast the baguette slices in the oven.
What to Serve with Slow Cooker French Onion Soup
Slow cooker French onion soup with cheesy baguette slices is already a filling stand-alone meal. The soup alone pairs nicely with a wide variety of dishes – enjoy it with a light salad or a serving of roasted vegetables. We love it with toasted psyllium husk bread instead of baguette for a low-carb option!
Serve smaller portions as a starter or side to a main dish. It’s delicious with bacon-wrapped chicken thighs, blackened pork chops, or tender steak. Don’t forget the drinks – French onion soup is best paired with chardonnay, white or red wine, or bourbon.
More Easy Soup Recipes To Try
- Slow cooker beef stew
- Keto beer cheese soup
- One-pot egg roll soup
- Slow cooker chicken zoodle soup
- Keto tom kha gai soup
If you make this slow cooker french onion soup, please leave a review. I really appreciate each and every 5-star rating and review comment!
Easy Crockpot French Onion Soup
Ingredients
- 2.5 pounds yellow onions thinly sliced
- 2 tablespoons butter unsalted
- 1 tablespoon olive oil
- 2 cloves garlic minced
- ½ cup dry white wine
- 6 cups beef broth or stock
- 2 whole bay leaves
- ½ teaspoon dried thyme
- ½ teaspoon salt
- ¼ teaspoon ground black pepper
- 8 slices baguette or gluten-free/low-carb French bread alternative
- 1 cup Gruyère cheese grated
Instructions
- In a skillet, melt the butter with olive oil over medium heat. Add the sliced onions and cook, stirring frequently, for about 10-15 minutes until they soften and start to caramelize. Add the garlic during the last minute of cooking. You can skip this step for a more hands-off approach, but caramelizing adds depth to the soup and I highly recommend it.
- Transfer the onions (caramelized or raw) to the slow cooker. Add the white wine, beef broth, bay leaves, thyme, salt, and pepper. Stir to combine.
- Cook on HIGH for 4-6 hours or LOW for 6-8 hours.
- With about 10 minutes left in the cooking time, preheat the oven broiler. Place the baguette slices on a baking sheet, sprinkle with grated Gruyère, and broil for 2-3 minutes until bubbly and golden brown. Watch carefully to avoid burning.
- Remove the bay leaves from the soup. Ladle the soup into bowls and top with a cheesy baguette slice. Serve immediately.
Notes
- The broth is the base of the soup, so use high-quality beef or chicken broth for the best flavor.
- Most broths and cheeses are already salty, so I recommend tasting your soup before adding salt to avoid over-seasoning.
- If you need to cook this soup quicker, try cooking it in a Dutch oven. It’s perfect for French onion soup, as it helps cook the onions evenly and retains heat for better flavor development.
- This soup gets even better the next day, so consider making it ahead of time and reheating it for a more developed flavor. Just store it in the fridge and reheat when you’re ready to enjoy.
Nutrition & Macros
To obtain the most accurate representation of the nutritional information in a given recipe, please calculate the nutritional information with the actual ingredients and amounts used, using your preferred nutrition calculator. Under no circumstances shall the this website and the author be responsible for any loss or damage resulting for your reliance on the given nutritional information.
