Slow Cooker French Onion Soup

Slow Cooker French Onion Soup is everything you dream of in a French onion soup.  The slow cooker will slowly caramelize the onions to perfection.  Just add broth and fresh herbs and continue to slow cook.  The onions will melt in your mouth and of course, topped with baguette and oozy French Gruyere cheese.

French Onion Soup is one of my favorite warming soups for fall and winter.  Using a slow cooker creates the perfect caramelized onions along with a deep, flavorful broth.  The toasted baguette will soak up the rich broth topped with bubbling gruyere.  

Caramelizing the Onions

Slicing the onions will be the most difficult part of this recipe.  It’s not hard, but you will probably shed a tear or two.  Using a mandolin will make the slicing a breeze.  I like to use sweet Walla Walla onions.  You can use whatever sweet onion you can find.  Slice 3-4 large onions.  

You will, also, need 1/2 cup of unsalted butter, 3 large cloves of garlic, 2 tablespoons coconut sugar, or brown sugar (this will help brown the onions nicely you can omit the sugar altogether if you wish).  Lastly just 1/2 teaspoon salt.  The broth used will add more salt to the soup.  It’s best to under salt because you can always add more to your liking.  Once the salt is in the soup, it can not be removed!  

Slow Cooker French Onion Soup

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1. In the bowl of a crockpot melt butter. 
2. Add sliced onions.
3. Sprinkle with the coconut sugar, 1/2 tsp. salt.  Stir to coat onions. 
4. Add chopped garlic to the top of the onions.   Cook on low for 6 hours. Stirring every 30 minutes or so.  
5. The onions will be reduced significantly in size and will be more golden in color.  Now that the onions are the perfect golden color, add the chicken and beef broth, 3-4 sprigs of fresh thyme, and a large bay leaf. Continue to cook for an additional 8 hours.  

In the meantime:

• Slice the baguette into 1-inch slices.  Butter both sides of the bread and place on a hot griddle or skillet.  Toast both sides.  
• Grate the gruyere cheese and set it aside.

The Finishing Touches

• After the soup has cooked for 8 hours, remove the thyme springs and bay leaves.  Discard.
• Add in fresh chopped thyme and parsley.  

Serving French Onion Soup

Ladle the hot soup into individual crocks, bowls, or mugs.  Top with enough of the toasted baguette to cover the top.  Load on the shredded gruyere and place under a hot broiler and cook until the cheese is melted and beginning to bubble.  Enjoy the warmth of this classic French Soup.

Just check out this oozy gooey cheese stretch.  Best! ❤️

5 from 25 votes

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Slow Cooker French Onion Soup

This Slow Cooker French Onion Soup recipe is everything you dream of in a French onion soup.  The crockpot will slowly caramelize the onions to perfection, with no need to cook on the stovetop first.  Just add broth and fresh herbs and continue to slow cook.  Top bowls with crispy baguette and oozy French Gruyere cheese for an elegant but effortless meal!

Course Appetizer, Dinner, Soup

Cuisine American, French

Keyword crock pot french onion soup, Crockpot French Onion Soup, French Onion Soup, Onion Soup, Slow Cooker French Onion Soup

Prep Time 15 minutes

Cook Time 12 hours

Total Time 12 hours 15 minutes

Servings 8 Servings

Calories 366 kcal

Author Janet Barton

Ingredients

• 3-4 large sweet onions organic, cut in half and sliced 1/8-1/4 inch thick
• 1/2 cup unsalted butter
• 1-2 tablespoons coconut sugar depending how sweet onions are
• 1/2 teaspoon salt
• 3 cloves garlic minced
• 4 cups chicken bone broth
• 4 cups beef bone broth
• 1-2 tablespoons Worcestershire sauce
• fresh thyme
• 1 bay leaf
• salt
• fresh ground white pepper
• fresh parsley
• 1 loaf French Baguette Slice into 1-inch thick slices
• 2-3 cups Gruyere cheese Shredded

Instructions

1. In the bowl of a crockpot melt butter. Add sliced onions, coconut sugar, 1/2 tsp. salt. Stir to coat onions. Add minced onions to the top of the onions.

2. Cook on low for 4-5 hours. Stirring every 30 minutes or so.

3. Add broths, about 4 sprigs of fresh thyme and 1 bay leaf.

4. Cover and continue to cook on low for an additional 8 hours.
5. Before serving add Worcestershire sauce to taste. Season with salt and white pepper and additional fresh herbs.

6. Slice baguette into 1-inch slices. Butter both sides and place on a hot griddle or skillet until golden brown.

7. Pour steaming hot soup into serving bowls. Top with 1-2 slices of baguette (enough to cover the top of the soup). Divide shredded gruyere cheese over the top of the baguette. Place under a broiler until cheese begins to bubble and is completely melted. Serve.

Recipe Notes

• Soup can cook for as long as 12 hours on low. 
• Can use 8 cups vegetable stock in place of Chicken and Beef broth.  
• I like to cook the onions during the day, then add the broth and cook through the night.
• Soup can be cooled and refrigerated for 3-4 days. Reheat when ready to serve.
• This recipe can serve up to 8 depending on the size of bowls and amounts used per serving.

Nutrition Facts

Slow Cooker French Onion Soup

Amount Per Serving

Calories 366 Calories from Fat 216

% Daily Value*

Fat 24g37%

Saturated Fat 14g70%

Trans Fat 1g

Polyunsaturated Fat 2g

Monounsaturated Fat 7g

Cholesterol 67mg22%

Sodium 553mg23%

Potassium 188mg5%

Carbohydrates 19g6%

Fiber 1g4%

Sugar 2g2%

Protein 19g38%

Vitamin A 670IU13%

Vitamin C 1mg1%

Calcium 371mg37%

Iron 1mg6%

* Percent Daily Values are based on a 2000 calorie diet.

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