Classic French Onion Soup Au Gratin with Cognac

It’s beefy with the right amount of salt, with crusty bread coated in thick bubbling slices of Gruyère cheese. The addition of Cognac elevates the taste and provides the right amount of alcohol, not too sweet like a Port, Red Wine, or Brandy. It’s super cozy, rich, and flavorful hot soup. The caramelized sweet onions are mellow and bright. This is the simplest and easiest French onion soup recipe I’ve made to date.

My husband claims that my onion soup is by far THE BEST he’s ever had. He begs me to make it every month.

Many restaurants make variations on this classic soup. Very few hit the spot. We make a point to order French onion soup from every restaurant that serves it. The running joke is that nobody can make a half decent cup of soup.

Secret Ingredients

I feel slight shame in admitting that my stock is not homemade. I haven’t boiled down beef bones for hours or days to get a delicious broth.

I’m using Better than Bouillon Roasted Beef Base!

I kid you not, it makes the soup. I seriously recommend you heading to your nearest store or Costco for a jar. I’m a big fan of the Beef Base and the Vegetable Base. I use it in many of my recipes. I should be a spokesperson! *wink wink*

The other secret ingredient is Cognac. It elevates the sophistication of the dish. You don’t need an expensive bottle of Cognac to do the trick. I recommend Cognac De Luze VS. It has really nice vanilla, honey, citrus tasting notes. It pairs really nicely with the saltiness of the beef base. My local spot ran out so I’m using Cognac Godet V.S Classique. This is a lively young cognac that’s double distilled in French oak casks. It has pear and leather notes on the nose. 

Modifications

Onions: Feel free to swap out sweet onions for yellow onions, red onions, or a combination. I chose sweet onions because I thought they tasted better.

Broth/Stock: Traditionally, French onion soup was not made vegetarian. It utilizes a beef base made from bones that have been cooked for hours or days. The beef stock adds a necessary flavor. I have made this soup utilizing the Better than Bouillon Vegetable Base and it definitely doesn’t hit the same but it’s still good. Feel free to add seasoning into your stock or use a chicken stock. Just note that it will be different from this classic simplified recipe. 

Cheese: Some people like to use grated parmesan, Swiss cheese, Comté or a combination of sliced or grated cheese. I prefer Gruyère or Comté.

Lets talk Bread

Do not spend a boatload of money on fancy bread. Traditionally, you use baguette. After a day or two you might be questioning your life choices. It’s now become a baseball bat baguette. It’s stale, hard as a rock.

And it’s PERFECT. Why? Nobody’s gonna know.

The bread is supposed to be stale and toasted. Back in peasant times, this was a cost saving measure to make your food stretch longer. To avoid waste. Poor peasants ate a lot of onions. It was cheap. And if you got stale day old bread, you had to make it taste good. 

Hence why you take all those leftover beef bones and boil the heck out of it. The gelatin and collagen in the bones are full of protein. If you’re poor, it’s not like you’re eating steak for dinner. 

The idea is that the beef stock needs to absorb into the bread. The worst possible idea is to use fresh bread because it will just become a soggy heavy mess. 

Be a peasant for a day and be pleasantly surprised!

Also, you don’t really need to use baguettes! 

I found a lovely high quality oatmeal bread locally on Too Good to Go. I used this instead and it’s totally fine and tasty! Do check out this app.. you’ll find a lot of great deals on day old bakery items. There’s a lovely wholesale bakery near me that does $5 bread bags on this app and they gave me 4 giant loaves of crusty bread, a bag of kaiser rolls, and 6 dinner rolls. I was in heaven! Plus you save food waste.

Ingredients

Sweet Onions: These are great for browning and caramelizing onions. It adds a sweet-savory taste to your broth. You may substitute with any kind of onion you choose. I think the sweet onions are the best for this dish.

Unsalted Butter: The beef base is pretty salty so you’ll want to watch any additional salt, especially if you’re on a low sodium diet.

Sugar: Helps to caramelize the onions.

Flour: This is added before any liquids are added so that it acts as a thickener for your soup. It can be substituted for a corn starch if you’re looking for a gluten free option.

Cognac: This is perhaps the absolute secret weapon in this recipe. The flavor enhances the onion and beef broth like nothing else!

Better than Bouillon Roasted Beef Base: A delicious broth option for those looking for a long-lasting staple in their refrigerator instead of storing a bunch of paper cartons of stock. It’s also the tastiest option I’ve used in this recipe.

Gruyere Cheese: The best and flavorful cheese that will melt under the broiler. Be sure to use a generous amount of cheese for best results!

Crusty Bread: Acts as a shelf for the cheese to stay above the broth line. It also gives you something tasty to nibble on. If you don’t have crusty bread slices, you can pull out some basic large croutons or whatever bread you like.

Storage

Store any leftovers in an airtight container and consume within 4 days. You can freeze the soup and consume it within 3 months.