Everyone will want to come home to this recipe for Crockpot French onion soup!
Slow cooker French Onion soup is an elegant and delicious way to warm up on a chilly day!
Fresh onions and herbs are slowly cooked in a robust beef broth flavored with sherry, then ladled into bowls and topping with cheesy bread. Gruyere or Emmentaler cheese makes this soup extra tasty! French onion soup is filling enough to serve as a meal on its own, or as an impressive first course.
Savory French Onion Soup
- French onion soup is a hearty meatless soup with bold flavors and a distinctive cheese bread topping that makes a perfect first course or can be served on its own with a side salad.
- Slow cooking allows for the flavors to blend over time on low heat for a rich soup with layers of savory flavor. Prep in the morning, set it, and forget it until it’s ready to serve!
- Basic ingredients that are likely already on hand and a couple of easy steps are all it takes to make this restaurant-worthy recipe.
- Keep this soup in the Crockpot and have a basket of garlic crostini so guests can top off their own bowls.
Ingredients and Variations
ONIONS: White onions are best for French onion soup because they are not overly sweet like red onions. Yellow onions can be used as well, even a combination of white and yellow will work.
BROTH: Beef broth gives French onion soup its classic, full-bodied flavor. A dash of sherry, port, or dry red wine balances out the salty broth and sweet onions with a little bit of acid. Non-alcohol substitutes for sherry are a 1:1 ratio of water to apple cider vinegar (or 1/8 cup of water and 1/8 cup of apple cider vinegar).
SEASONINGS: Fresh thyme has a subtle, herbal flavor and fragrance – use fresh if you can but dried is okay. If adding meat to bulk up the soup, mix in some homemade Italian seasoning mix to intensify the broth.
CHEESE: Cheese is what makes French onion soup such a timeless classic dish! Gruyere and Emmentaler have bright and tangy flavors with the perfect “meltability” on the slices of bread. If they aren’t available, Swiss, mozzarella, or parmesan cheese work great, too!
EXTRAS: Budget-friendly extras like beans, leftover chicken, frozen meatballs, or ground Italian pork sausage will bulk up French onion soup without it losing its classic savory flavor.
How to Make French Onion Soup in a Crockpot
Just follow these easy steps for the best onion soup ever!
- Toss onions with butter in the crockpot. Add bread cubes, broth, sherry and thyme (as per recipe below).
- Cook until onions are soft and cooked through; 10-18 hours on low or 4-7 hours on high.
- Before serving, broil sliced French bread on both sides.
SERVING OPTION #1: Ladle soup into bowls and top with broiled bread, shredded cheese and place the bowls under the broiler until the cheese is browned and bubbly.
SERVING OPTION #2: Sprinkle cheese on bread and broil until browned and then place each piece on top of a bowl of soup.
What to Serve with French Onion Soup
Storing Leftover French Onion Soup
- Keep leftover French onion soup separate from any leftover cheese bread in a covered container for up to 4 days. Reheat on the stove.
- Use leftover soup as a “jus” for dipping roast beef sandwiches in, or add macaroni, orzo, rice, and a bag of frozen spinach to create a whole new meal!
Crockpot French Onion Soup
- 3 pounds onions peeled and thinly sliced
- ½ cup butter melted
- 4 cups cubed french bread 6-8 slices
- 4-5 cups beef broth , extra as needed
- ¼ cup sherry or port, optional
- 2 sprigs fresh thyme optional
- 6-8 slices french bread or baguette slices
- 1 cup shredded gruyere cheese *
- 1 cup shredded emmentaler cheese *
- Place sliced onions in the slow cooker. Pour in butter and toss to coat. Add bread cubes, then pour enough broth in to cover. Stir well. Add sherry and a sprig of thyme, if using. Add additional broth to cover if needed.
- Cover and cook for low for 10-18 hours, or high for 4-7 hours, or until onions are soft and cooked through. Stir occasionally. Remove thyme sprigs once soup is cooked.
- Shortly before serving, preheat oven to broil. Broil slices of french bread for 2 minutes on each side.
- Ladle soup into bowls and add a piece of the broiled bread. Top bowls with cheese, and pop under the broiler. Heat until cheese is browned and bubbling and serve.
- Sprinkle each piece of bread with cheese and broil for 1 minute.
- Ladle soup into bowls, top with cheesy bread, and serve.
- Garnish with thyme leaves or chopped parsley if desired.
Nutrition information does not include optional ingredients or garnish and is an estimate. It may change based on actual ingredients and cooking methods used.
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