Caramelized French Onion Soup (Print Version)

Rich onion soup with slow-caramelized onions and cheesy sourdough crostini, perfect for chilly days.

# What 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
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)

# How to Make It:

01 - In a large heavy-bottomed pot, melt butter and olive oil over medium heat.
02 - Add sliced onions, sugar, salt, and pepper. Cook, stirring frequently, for 35 to 45 minutes until onions are deep golden and 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 create a roux base.
05 - Pour in white wine, scraping up any browned 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 as needed. Discard thyme sprigs and bay leaf before serving.
07 - While soup simmers, preheat oven to 400°F. Arrange baguette slices on a baking sheet, brush with olive oil, and toast for 5 to 7 minutes until golden brown.
08 - Top toasted sourdough slices with Gruyere cheese and optional Parmesan. Return to oven and bake until cheese is melted and bubbly, 3 to 4 minutes.
09 - Ladle soup into oven-safe bowls, place crostini on top, and optionally broil for 1 to 2 minutes for extra cheese melt. Serve immediately while hot.

# Additional Tips::

01 -
  • The onions melt into pure sweetness without any burnt bitterness when you take your time—no rushing, no regrets.
  • Those cheesy crostini become the moment when someone's face lights up at the table, every single time.
  • It tastes like you spent hours cooking but honestly takes less time than you'd think.
02 -
  • Onions release water before they brown, so if you rush the heat trying to speed things up, you'll just boil them instead—low and slow is the only way this works.
  • Tasting the broth before you use it is non-negotiable because some broths are so salty they'll wreck everything, and you can't fix it once it's in the pot.
03 -
  • If your onions aren't getting dark after 40 minutes, increase the heat slightly—some pots cook faster than others, and you can adjust as you go.
  • Make sure your soup bowls are oven-safe if you're planning to broil them; regular ceramic will crack under the broiler heat.
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