The BEST French Onion Soup Recipe (AKA My Mom's)

The BEST French Onion Soup. Image by Christianne Klein

This is one of my favorite recipes of all time.  My mom always made this soup for special occasions when I was growing up, and it's now a classic in our family. Over the years my mom switched out the classic baguette for sourdough and changed basic beef broth to an unctuous consommé of beef.  Trust me, you want to track down consommé of beef.  It makes a world of difference. 

This recipe is great as is, but depending on what I have on hand (or my mood) I switch out some of the Swiss cheese for freshly grated gruyere; add a splash of brandy to deglaze the onion pan before adding the onion mix to the broth; or sometimes change out a yellow onion for a sweet onion and add a shallot.  I love that it adds another few layers to an already magical soup. 

Fun bonus: This is the best French Onion soup recipe in the world andddd incredibly easy to make.  

Below is my mom’s original recipe: 

Ingredients:

One stick butter

5 large yellow onions- sliced 

5 cans consommé of beef (add water as directed)

1¼ lb. Swiss cheese, freshly grated

8 oz. parmesan cheese, freshly grated

Sliced sourdough bread toasted (browned and slightly charred)

2 tablespoons Worcestershire sauce 

Instructions:

Onions at the "golden brown" stage. Image by Christianne Klein.

Heat butter in a large sauté pan over medium heat. Add the sliced onions and cook, stirring often, until they become golden brown and caramelized (about 30 minutes). Some onions should be dark brown, nearly charred.  At the same time, heat the consommé of beef with Worcestershire sauce in a large pot. 

Add cooked onions to consommé of beef and Worcestershire sauce broth and simmer for 20-30 minutes for flavors to combine.

While the soup is simmering, toast sourdough bread to golden brown (some parts of the toast should be dark brown).

Grate Swiss cheese and parmesan into two separate dishes.

Ladle the soup into broiler-proof bowls. 

Place sourdough toast on top of soup in bowls. 

Sprinkle generous amounts of freshly grated Swiss cheese on top of the sourdough toast. Add parmesan cheese on top of the Swiss cheese. 

Place bowls on a baking sheet and position them under the broiler until the cheese is melted and bubbly, achieving a deep golden brown crust (usually 3-5 minutes). Monitor this step closely to prevent burning or overflow.

Carefully remove from the oven (bowls will be hot), and let soup cool for a few minutes before serving.

Enjoy!