Caramelized Onion Soup with Swiss Cheese Basil Croutons

Warm up with this soul-soothing Caramelized Onion Soup with Swiss Cheese Basil Croutons, a gourmet twist on the classic French onion soup. This recipe features deeply caramelized yellow onions simmered in a rich beef broth infused with dry white wine, fresh thyme, and a hint of sweetness. The star topping—crispy baguette croutons layered with gooey Swiss cheese and fragrant basil—adds an irresistible flavor and texture to every bite. Perfect for cozy dinners or an elegant starter, this recipe balances savory depth with herbaceous notes, making it a standout dish. Ready in just under 1.5 hours, it’s the ultimate comfort food for a chilly evening. Keywords: caramelized onion soup, Swiss cheese croutons, basil, beef broth soup, homemade French onion soup.

Nutriscore Rating: 69/100

Prep Time:15 mins

Cook Time:75 mins

Total Time:90 mins

Servings: 4

Ingredients

• 4 tablespoons unsalted butter
• 2 tablespoons olive oil
• 6 large yellow onions
• 1 teaspoon salt
• 1 teaspoon granulated sugar
• 1 cup dry white wine
• 6 cups beef broth
• 1 bay leaf
• 4 sprigs fresh thyme
• 1 small loaf baguette
• 1 cup Swiss cheese
• 6 fresh basil leaves
• 1 garlic clove
• 0.5 teaspoons black pepper

Directions

Step 1

Peel and slice the yellow onions thinly into half-moon shapes.

Step 2

In a large pot or Dutch oven, melt the butter with the olive oil over medium heat.

Step 3

Add the sliced onions and cook them for 5 minutes, stirring occasionally.

Step 4

Sprinkle the onions with salt and sugar, then lower the heat to medium-low.

Step 5

Cook the onions, stirring frequently, for 45 minutes or until deeply caramelized and golden brown.

Step 6

Pour in the white wine to deglaze the pan, scraping up any browned bits from the bottom. Simmer for 3 minutes or until the wine is mostly reduced.

Step 7

Add the beef broth, bay leaf, and thyme sprigs. Bring the mixture to a boil, then reduce the heat and simmer gently for 20 minutes.

Step 8

Season with black pepper to taste, and discard the thyme sprigs and bay leaf before serving.

Step 9

While the soup simmers, prepare the croutons: Preheat your oven to 375°F (190°C).

Step 10

Slice the baguette into 1/2-inch thick slices, and place them on a baking sheet.

Step 11

Rub one side of each slice with a cut garlic clove for subtle flavor.

Step 12

Sprinkle a generous amount of shredded Swiss cheese and place one basil leaf on each slice.

Step 13

Bake the croutons for 8-10 minutes, or until the cheese is fully melted and golden.

Step 14

To serve, ladle the soup into bowls and top each bowl with 1-2 croutons. Serve immediately and enjoy.

Nutrition Facts

Serving size	(3189.5g)

Amount per serving	% Daily Value*
Calories	2071.0

Total Fat 91.5g	0%
Saturated Fat 38.7g	0%
Polyunsaturated Fat 3.0g
Cholesterol 161.8mg	0%
Sodium 8962.4mg	0%
Total Carbohydrate 196.3g	0%
Dietary Fiber 29.7g	0%
Total Sugars 53.9g
Protein 85.0g	0%

Vitamin D 4.3IU	0%
Calcium 1836.6mg	0%
Iron 21.7mg	0%
Potassium 3586.5mg	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: 42.3%

Protein: 17.4%

Carbs: 40.3%