Caramelized French Onion Soup (Printable Version)

A rich blend of caramelized onions and savory broth topped with melted Gruyere crostini for warm winter comfort.

# The Ingredients You'll Need:

→ For the Soup

01 - 6 large yellow onions, thinly sliced
02 - 3 tablespoons unsalted butter
03 - 1 tablespoon olive oil
04 - 1 teaspoon sugar
05 - 1 teaspoon salt
06 - 1/2 teaspoon freshly ground black pepper
07 - 2 cloves garlic, minced
08 - 2 tablespoons all-purpose flour
09 - 1/2 cup dry white wine
10 - 6 cups beef broth or vegetable broth for vegetarian option
11 - 2 sprigs fresh thyme or 1/2 teaspoon dried thyme
12 - 1 bay leaf
13 - Salt and pepper to taste

→ For the Sourdough Gruyere Crostini

14 - 1 small sourdough baguette, sliced into 1/2-inch rounds
15 - 2 tablespoons olive oil
16 - 1 cup Gruyere cheese, grated
17 - 1/2 cup Parmesan cheese, grated (optional)

# Step-by-Step Instructions:

01 - In a large heavy-bottomed pot, melt butter and olive oil over medium heat until foaming.
02 - Add sliced onions, sugar, salt, and pepper. Cook, stirring frequently, for 35 to 45 minutes until onions are deep golden and fully caramelized.
03 - Stir in the minced garlic and cook for 1 minute until fragrant.
04 - Sprinkle flour over onions and cook, stirring constantly, for 2 minutes to eliminate raw flour taste.
05 - Pour in dry white wine, scraping up any caramelized bits from the pot bottom. Simmer for 2 to 3 minutes to reduce slightly.
06 - Add beef broth, thyme sprigs, and bay leaf. Bring to a gentle boil, then reduce heat and simmer uncovered for 25 to 30 minutes. Adjust seasoning with salt and pepper. Remove and discard thyme sprigs and bay leaf.
07 - While soup simmers, preheat oven to 400 degrees Fahrenheit. Arrange baguette slices on a baking sheet, brush with olive oil, and toast for 5 to 7 minutes until golden brown.
08 - Top each toast with grated Gruyere and optional Parmesan. Return to oven and bake for 3 to 4 minutes until cheese is melted and bubbly.
09 - Ladle soup into oven-safe bowls and place crostini on top. Optional: broil for 1 to 2 minutes for additional cheese melting. Serve immediately while hot.

# Additional Tips::

01 -
  • The caramelization is patient work, but those deep golden onions create a richness that tastes like it took hours, even though it's straightforward.
  • There's something oddly satisfying about ladling soup into a bowl and knowing the crostini waiting on top will melt into something creamy and crispy at once.
02 -
  • The caramelization step is where people rush and regret it; keeping the heat at medium and stirring every few minutes means you get those deep flavors instead of burnt edges.
  • Don't skip toasting the crostini separately first, because bread added directly to soup gets soggy immediately, and no one wants a falling-apart open-faced sandwich in their bowl.
03 -
  • Don't add the wine until the onions are truly caramelized, because acid can slow the browning process and you'll end up with cooked onions instead of caramelized ones.
  • Grate your own cheese instead of using pre-shredded, because the anti-caking agents in store-bought grated cheese prevent it from melting as smoothly.
Return to Recipe