Description
A rich and savory Slow Cooker French Onion Soup featuring caramelized sweet onions, beef broth, and a blend of aromatic herbs. This comforting recipe includes homemade garlic croutons and melty Swiss cheese, perfect for a cozy meal.
Ingredients
Scale
Soup Ingredients
- 1 stick butter
- 5 sweet yellow onions, sliced (white, yellow, or red onions can be used)
- 1 tsp salt
- 1/4 tsp pepper
- 1/4 cup flour
- 64 oz beef broth or beef stock (two 32-oz. containers)
- 1 tsp sugar (optional, only if onions are not sweet)
- 2 tsp minced garlic
- 1/4 tsp dried thyme (not ground)
- 1/4 tsp dried oregano (not ground)
- 1 tsp Worcestershire sauce
- 1 Tbsp balsamic vinegar
- 1 bay leaf
For Serving
- 1 baguette
- Olive oil
- 1 whole garlic clove
- Sliced Swiss cheese (about 2 slices per serving; can use provolone or gruyere)
- Shredded Parmesan cheese (about 1 tablespoon per serving)
Instructions
- Caramelize Onions: In a large skillet over medium-high heat, melt the butter. Add the sliced onions and sprinkle with salt and pepper. Sauté the onions, stirring often, for about 10 minutes until browned and caramelized. Adjust heat as needed to prevent burning.
- Add Flour: Stir the flour into the butter and caramelized onions and cook for 2 minutes to form a roux.
- Transfer to Slow Cooker: Pour the floured onions into the slow cooker. Add beef broth, sugar (if using), minced garlic, dried thyme, dried oregano, Worcestershire sauce, balsamic vinegar, and place the bay leaf on top. Stir well to combine.
- Cook Soup: Cover and cook on HIGH for 4 hours or on LOW for 8 hours until flavors meld.
- Prepare Croutons: Preheat oven to 500°F with the broiler setting. Slice the baguette into 1/4-inch slices and arrange on a sheet pan. Brush the slices with olive oil using a pastry brush. Broil for 3-5 minutes or until toasted and browned. Once toasted, rub each slice with the cut side of a garlic clove to infuse garlic flavor.
- Assemble Bowls: Remove bay leaf from soup. Ladle soup into ovenproof bowls placed on a sheet pan or pie tin. Top each bowl with several homemade croutons, 1-2 slices of Swiss cheese (or provolone/gruyere), and sprinkle with shredded Parmesan cheese.
- Broil to Finish: Place the bowls under the broiler until the cheese melts, bubbles, and turns golden brown.
Notes
- Freeze leftover soup without croutons or cheese for up to 3 months. Cool completely before storing in freezer-safe bags or containers.
- Thaw frozen soup overnight in the refrigerator and reheat on the stove or in the microwave.
- Adjust sugar usage based on the sweetness of the onions; omit if using naturally sweet onions.
- For a vegetarian version, substitute beef broth with vegetable broth and omit Worcestershire sauce or use a vegetarian-friendly brand.
Nutrition
- Serving Size: 1 cup soup with croutons and cheese
- Calories: 290
- Sugar: 6g
- Sodium: 700mg
- Fat: 18g
- Saturated Fat: 9g
- Unsaturated Fat: 7g
- Trans Fat: 0g
- Carbohydrates: 22g
- Fiber: 2g
- Protein: 10g
- Cholesterol: 35mg
