Classic French Onion Soup

This classic French onion soup is comforting and timeless. Slowly cooked onions, rich beef broth, and toasted bread topped with melted cheese come together to make a cozy soup that still feels a little special.

This French onion soup recipe is old enough that it came from a time back when they filled your tank, checked the oil, washed the windows, and had competitive giveaways, including recipe cards. As a kid, my brother let me tag along to choose the free recipe cards, and this is one of them.

I felt like a grown-up whenever I made this soup. It felt so fancy at the time, and it still holds a lot of fond memories for me.

Classic French Onion Soup Recipe Ingredients

Ingredient Note:
A good-quality beef broth works well for this soup. Using a low-sodium broth makes it easier to adjust the seasoning at the end.

How to Make Classic French Onion Soup

Step 1 – Prepare the Onions

Slice the onions into half-rings. To help reduce watery eyes, cut off the ends, remove the skins, and rinse each onion under cold water before slicing. You can cover the sliced onions with a clean tea towel or a damp paper towel while you work.

Step 2 – Cook the Onion Base

Melt the butter in a large heavy pot over medium heat. Add the onions and stir to coat them in the butter. Cook slowly, stirring often, until the onions are soft, golden, and sweet, which usually takes about 45 to 60 minutes. Season lightly with salt and pepper as they cook.

Cooking the onions slowly is what gives French onion soup its deep, rich flavor. Rushing this step will leave the onions sharp instead of sweet, so it is worth taking your time here.

Slow Cooker Note
If you prefer, the onions can be cooked in a slow cooker instead. Add the butter and sliced onions to the slow cooker and cook on low until the onions are soft and sweet. Once cooked, return them to a pot on the stove to continue with the recipe.

Step 3 – Finish the Soup

Add the beef broth and cognac, brandy, or red wine. Bring the soup to a gentle simmer and let it cook for about 30 minutes. Taste and adjust seasoning with salt and pepper if needed.

Step 4 – Prepare the Bread and Cheese

Slice the French bread at least 1/2 inch thick and trim it to fit your soup bowls. In a small bowl, mix the butter and crushed garlic together. Spread the garlic butter on the bread and toast under the broiler until lightly golden.

Grate the mozzarella and Parmesan cheese and set aside.

Step 5 – Assemble and Broil

Just before serving, ladle the hot soup into oven-proof bowls. Float a piece of toasted bread on top of each bowl and sprinkle with both cheeses.

Place the bowls on a baking sheet and put them under the broiler until the cheese is melted and lightly golden. This only takes a few minutes, so watch closely. Carefully remove from the oven and serve hot, as both the soup and bowls will be very hot.

Make Ahead Tip

The onion base can be made ahead of time and reheated when needed. Add the beef broth, toast the bread, and add the cheese just before serving so everything stays fresh.

Serving Suggestions

When I first saw this recipe, French onion soup was something you only enjoyed at an upscale restaurant, usually as a paid add on before the main meal. It still makes me feel a bit fancy every time I serve it at home.

You do not have to use French onion soup tureens to serve this soup, but they are nice if you have them. I have a set that is decades old, but you can still find them at places like the dollar store. They help hold the heat and make the soup feel a little special.

If you want to save this classic French onion soup recipe for later, be sure to pin it to your favorite soup or comfort food board. It’s one of those recipes that’s always nice to have tucked away for a cozy day.

More Easy Soup Recipes

If you enjoy cozy homemade soups, here are a few more favorites you might like: