This traditional French Onion Soup has warm baguettes topped with hot, melted Gruyere cheese. High quality beef broth, a splash of wine, and perfectly caramelized onions are the secrets to this classic recipe.
Slice the onions into strings of medium-size. They'll shrink down and you don't want them too thin. (Using a mandoline slicer makes this much easier).
The onions will caramelize slowly, this takes patience. 6 large onions could take over an hour to fully caramelize. Stir the onions every 20 minutes or so until they've reached your desired size and color.
Add the white wine, increase the heat to medium, and cook for an additional 2-3 minutes. Pour in the beef and chicken broth and add the bay leaves and thyme. Simmer for another 45 minutes, with the lid cracked.
While the soup simmers, preheat the oven to 350 degrees. Slice the baguette into ½ inch thick slices. Brush the tops with olive oil if desired. Plan on using 1-2 slices per bowl depending on the width of the bread and the bowls you are using.
Increase the oven temperature to a low broil. Top each baguette with cheese and bake in the oven until the cheese melts and begins to bubble and brown slightly.
Remove the bay leaves and thyme stems. Season to taste with salt and pepper.
Ladle the warm soup into each bowl and use tongs to top each of them with the warm baguettes. Top with thyme if desired and serve!
Other cheese options include Comte, Emmental (Swiss), and/or Provolone.
A splash of Worcestershire sauce can be added when the beef broth is added as well.
Crock Pot Method: Once the onions are caramelized as shown above, transfer them to a Crock pot. Add remaining ingredients and cook on low for 6-8 hours or high for 4-5 hours.
Check out my Instant Pot French Onion Soup recipe!