The Best Healthy French Onion Soup

Two bowls of healthy French onion soup on a wooden board with thyme ,a blue napkin and a bronze spoon nearby.

4.84 from 6 votes

This Healthy French Onion Soup is a delicious twist on a classic recipe that doesn't compromise on flavor. The satisfying combination of caramelized onions, gooey cheese, and savory broth is perfect for cozy nights.

Prep Time15

Cook Time1 20

Total Time1 35

Course: Soups

Cuisine: American, French

Servings:

Calories: 310kcal

Author: Dr. Sonali Ruder

Equipment

Ingredients

1 tablespoon olive oil
1 tablespoon butter
2 ½ lbs. yellow onions (about 3 large onions), thinly sliced (about 8 cups sliced)
½ teaspoon kosher salt plus extra to taste
¼ teaspoon black pepper
½ teaspoon sugar
2 cloves garlic, minced
3 sprigs fresh thyme (or ½ teaspoon dried thyme)
1 bay leaf
1 tablespoon flour
1 cup dry white wine (like sauvignon blanc or pinot grigio)
8 cups reduced-sodium beef broth (can substitute chicken or vegetable broth)
1 tablespoon cognac (can substitute brandy or dry sherry)
6 slices baguette (preferably multigrain)
3 ounces Gruyere cheese, grated

US Customary - Metric

Instructions

Heat the oil in a large Dutch oven over medium heat and add the onions. Stir to coat the onions with the oil. Season the onions with the salt, pepper, and sugar.
Cook, stirring occasionally with a wooden spoon, until the onions are golden brown and caramelized, about 45 minutes. Take your time with this step as this is what’s going to provide the rich flavor for your soup. If the onions start to burn or catch bottom, add a small amount of water and scrape up any brown bits from the bottom of the pot with a wooden spoon.
Once the onions are caramelized, add the garlic, thyme and bay leaf. Cook another minute or two and then stir in the flour. Cook, stirring constantly, another minute.
Turn the heat up to high and add the wine. Cook until almost all of the liquid has evaporated and the onions are jammy. Add the beef broth. Bring to a boil and reduce to a simmer. Simmer the soup, partially covered, 30 minutes. When the soup is done, add the cognac, if using. Taste and adjust seasoning with salt and pepper. Remove thyme sprigs and bay leaf.
While soup is cooking, preheat oven to 400°F.
Cut the bread into large cubes. Place them on a baking sheet and bake in the oven until lightly toasted, 7-8 minutes. Remove from oven and set aside.
Place 6 oven-safe soup bowls on a baking sheet ladle the soup into the bowls. Top each bowl with a handful of toasted bread cubes and sprinkle evenly with the grated cheese. Place the baking sheet in the oven under the broiler and broil until cheese is melted and bubbly around the edges, 3-4 minutes. Let the soup cool a few minutes before serving.
If you don't have oven-proof bowls, you can sprinkle the cheese on the toasted bread cubes and place it under the broiler to melt. Then, top the soup with the cheesy bread.

Notes

Classic French onion soup is topped with baguette slices but I like to cut my baguette into croutons instead. It's easier to eat than trying to break up the bread with a spoon.

If you don't have oven-proof bowls, you can sprinkle the cheese on the toasted bread cubes and place it under the broiler to melt. Then, top the soup with the cheesy bread.

This healthy French onion soup develops more flavor over time so it's the perfect soup to make the day before and store in the fridge. Make the cheesy toast fresh when you're ready to serve the dish.

If your soup hasn't developed a rich flavor, you can add a splash of balsamic vinegar or Worcestershire sauce at the end for a boost of umami.

Nutrition