Slow Cooker French Onion Soup

Warm up your home with the luxurious aroma of Slow Cooker French Onion Soup—a comforting, slow-simmered classic that's rich in flavor and perfect for cozy nights. This recipe combines the deep caramelized sweetness of golden yellow onions with the robust flavors of beef stock, thyme, and a touch of dry white wine for added depth. The slow cooker does all the heavy lifting, gently melding the ingredients into a fragrant, velvety soup over hours. Finished with golden, broiled baguette slices and a decadent layer of melted Gruyère and Parmesan cheese, this dish is as indulgent as it is easy to make. With minimal prep and an ultra-satisfying result, this recipe is perfect for busy weekdays or an impressive dinner party starter. Let your slow cooker transform simple pantry staples into a gourmet masterpiece!

Nutriscore Rating: 63/100

Prep Time:20 mins

Cook Time:480 mins

Total Time:500 mins

Servings: 6

Ingredients

• 5 large Yellow onions
• 4 tablespoons Unsalted butter
• 1 tablespoon Olive oil
• 2 minced Garlic cloves
• 1 teaspoon Brown sugar
• 6 cups Beef stock
• 1 cup Dry white wine (optional)
• 1 leaf Bay leaf
• 2 sprigs Thyme sprigs
• 1 teaspoon Salt
• 0.5 teaspoon Black pepper
• 1 loaf French baguette
• 2 cups, shredded Gruyère cheese
• 0.5 cup, shredded Parmesan cheese

Directions

Step 1

Peel and thinly slice the yellow onions into even slices.

Step 2

In a large skillet, melt butter and olive oil over medium heat. Add the sliced onions and cook for 10-15 minutes until softened, stirring occasionally.

Step 3

Add minced garlic and brown sugar to the skillet with the onions. Stir well and continue cooking for another 10-15 minutes, until the onions are caramelized and golden brown. Adjust heat to avoid burning.

Step 4

Transfer the caramelized onions to a slow cooker. Add beef stock, white wine (if using), bay leaf, thyme sprigs, salt, and black pepper. Stir gently to combine.

Step 5

Cover and cook on low for 7-8 hours, or on high for 4-5 hours, until the flavors are fully combined and the soup is rich and fragrant.

Step 6

30 minutes before serving, preheat the oven broiler on high. Slice the French baguette into 1-inch-thick pieces and place them on a baking sheet. Toast under the broiler for 1-2 minutes on each side until golden brown and crisp.

Step 7

Ladle the hot soup into oven-safe bowls. Top each bowl with a slice or two of toasted baguette and sprinkle shredded Gruyère and Parmesan cheese over the top.

Step 8

Place the bowls on a baking sheet and broil in the oven for 2-4 minutes, or until the cheese is melted, bubbly, and lightly golden.

Step 9

Carefully remove the bowls from the oven and let cool for a few minutes. Serve immediately and enjoy!

Nutrition Facts

Serving size	(2829.3g)

Amount per serving	% Daily Value*
Calories	2439.7

Total Fat 165.5g	0%
Saturated Fat 90.9g	0%
Polyunsaturated Fat 6.0g
Cholesterol 458.9mg	0%
Sodium 9973.2mg	0%
Total Carbohydrate 86.7g	0%
Dietary Fiber 13.8g	0%
Total Sugars 38.1g
Protein 120.4g	0%

Vitamin D 63.4IU	0%
Calcium 3410.5mg	0%
Iron 5.5mg	0%
Potassium 2323.2mg	0%

*The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.

Source of Calories

Fat: 64.3%

Protein: 20.8%

Carbs: 15.0%