Caramelized Onion Soup with Swiss Cheese-and-Basil Croutons Recipe

20 Minutes
1 Hour, 9 Minutes


Makes 8 cups

French onion soup gets a flavor update with basil-flavored, crusty croutons. Caramelized onions give a touch of sweetness to this delicious soup. Although onion soup is relatively popular, most people get it wrong. It all comes down to how the onions and broth are cooked, which can be a hit or miss if you neglect any steps. That’s why patience is key here if you want to achieve a powerhouse bowl of onion soup. With about an hour cook time, there’s no reason to take any shortcuts. When it comes to caramelizing onions to perfection, it takes time. But, it’s totally worth the wait. Just think of the rich, flavorful bowl that will await you. Coat a large Dutch oven with olive oil. Bring the pan to a medium heat, stirring in thinly sliced onions. Once the onions are soft, remove the lid and allow them to cook low and slow to generate that sweet flavor and golden brown color. When the onions turn brown and are reduced in size, add garlic, water, beef bouillon granules, seasonings, and dry sherry (if you’d like) to make up the broth. Bring to a boil, and simmer for 20 minutes. When done, the soup should be thick and flavorful. Ladle soup into oven-safe serving bowls, and place on a baking sheet. Next up are the baguette slices. Cut French baguette diagonally into 8 slices, and mix together Swiss cheese, basil, and mayonnaise. Spread the delicious mixture on one side of the bread slices, topping the soup with bread slices, cheese side up. Broil until the cheese is melted, brown, and bubbly. The soup is great on its own, but the addition of cheesy and toasted baguette is what makes this recipe extra special.


  • 6 medium onions, halved and thinly sliced
  • 1/4 cup olive oil
  • 4 garlic cloves, pressed
  • 3 tablespoons beef bouillon granules
  • 1 teaspoon pepper
  • 1 teaspoon chopped fresh thyme
  • 2 tablespoons dry sherry (optional)
  • 1 (8-oz.) French baguette
  • 1 cup (4 oz.) finely shredded Swiss cheese
  • 2 tablespoons chopped fresh basil
  • 2 tablespoons mayonnaise

How to Make

  1. Cook sliced onions in hot oil in a Dutch oven over medium-high, stirring occasionally, 20 to 25 minutes or until onions are golden brown. Add garlic, and cook 1 minute. Stir in 8 cups water, bouillon granules, pepper, and thyme. Add sherry, if desired. Bring to a boil. Cover, reduce heat to low, and simmer, stirring occasionally, 20 minutes.
  2. Ladle soup into oven-safe serving bowls, and place on a baking sheet.
  3. Cut baguette diagonally into 8 slices. Stir together Swiss cheese, basil, and mayonnaise. Spread mixture on 1 side of bread slices. Top soup with bread slices, cheese side up.
  4. Broil 5 inches from heat 2 1/2 to 3 minutes or until lightly browned. Serve immediately.