Classic French Onion Soup is a perfect union of caramelized onions, crusty french bread, and bubbly melted cheese. Our tried-and-true, easy-to-make recipe is rich, savory, and satisfying to the bone.
In a 10-inch Enameled Cast Iron Dutch Oven (or other large, heavy-bottom saucepan) melt 2 tablespoons olive oil and 2 tablespoons butter over medium-low heat. Add sliced red or yellow onions to melted oil and butter.Cook slowly, stirring frequently, over medium-low heat until onions are very soft and have turned dark golden brown. Caramelizing the onions should take at least 45 minutes. DO NOT RUSH or your onions may turn out bitter.Foolproof step-by-step directions for caramelizing onions can be found on our post, Slow Cooker Caramelized Onions.
TO USE PRE-PREPPED CARAMELIZED ONIONS(which we heartily encourage you to do!): Skip the step outlined above and just add 2 cups (16 ounces) pre-prepped caramelized onions to the Dutch Oven. Heat over medium-low until the onions are bubbly; about 5 minutes.
Soup Base
To the prepared caramelized onions, add the wine and deglaze the pan. Bring to a simmer over medium-low heat. Stir in garlic, thyme leaves (or dried thyme), and freshly ground pepper. Reduce the heat and simmer on low until the wine has evaporated and the onions are nearly dry; about 5 minutes.
Add the beef stock and Worcestershire sauce.Return soup to heat and allow to simmer 10 minutes more. Season to taste.
Baguette Croutons
While soup is simmering, arrange baguette slices on a baking sheet in a single layer. Set under broiler just long enough to toast lightly; about 2 minutes. Flip the baguette rounds over and repeat. Rub one side of each toasted bread slice with a clove of garlic.
Serving
When you are ready to serve, ladle hot soup into oven-safe bowls. Float one or more prepared baguette croutons on top. Sprinkle generously with grated cheeses. Place under broiler just long enough to melt and slightly brown the cheese.
Garnish with fresh thyme sprigs and serve.
Notes
Wine & Wine Substitutes: We like our French Onion Soup slightly lighter and on the sweet side: a good Reisling works very nicely.If you are not a wine-drinker and prefer not to buy it, you can use equal parts additional broth and white grape juice in place of the wine.