A traditional French Onion Soup with a savory twist? Hot roasted bone marrow spooned on top of melted cheese, all over a bowl of slow-cooked caramelized onions in a rich broth. This takes the classic favorite to a whole new level.
French onion soup is about as classic as you can get in the world of soups. The base idea behind this classic soup has a history all the way back to the Romans. However, it is one that we don’t see a lot of people coming back to often. We started to wonder why, as the idea of simmered onions in a flavorful beef broth sounds pretty comforting to me on chilly days.
Perhaps it’s that people aren’t too fond of ‘onions’ these days. Or that we have more options out there than the early creators did. Either way, onions are often cheap, and we wanted to see just how many people we could get raving about this recipe (Turns out, quite a few).
This easy French Onion Soup recipe has a ton of rich flavor and is topped with gooey cheese. It’s the perfect way to warm up on a chilly day, just like our Slow Cooker Creamy Chicken Noodle Soup and Cheesy Cauliflower and Ham Soup.
What Is Bone Marrow French Onion Soup?
Bone Marrow French Onion Soup is a luxurious twist on the classic French Onion Soup recipe. In this recipe, onions are slow-cooked to perfection, creating a rich, flavorful base. The addition of roasted bone marrow adds a decadent depth and velvety texture, elevating the soup to a new level of indulgence. Covered in crispy bread and melted raclette, every bite bursts with a harmonious blend of savory, sweet, and umami notes, creating a dining experience that lingers in the memory.
Homemade French Onion Soup Recipe Ingredients
- Onions – We used Vadallia onions, and the rest were bulk yellow onions.
- Unsalted butter
- Water plus extra for deglazing
- Red wine
- Chicken broth
- Beef broth
- Bay leaf
- Fresh Thyme
- Roasted beef marrow bones
- Slices hearty bread
How to Make French Onion Soup with Bone Marrow
We turn the classic into the best French onion soup by slowly caramelizing the onions and adding bone marrow to give it a robust meaty umami flavor. It’s a great recipe for chilly weather or serving at a dinner party.
- Preheat your oven to 400 degrees F. Grab your big 7-quart or larger Dutch oven. It might seem big, but this recipe makes a TON. Melt some butter in there.
- Take it off the heat and toss in the onions and a teaspoon of salt, making sure they’re well coated.
- Pop that Dutch oven in the lower center rack of your oven, cover it, and let it heat up for an hour.
- Take it out, give it a good stir, and scrape the sides and bottom of the pot.
- Put it back in the oven for another 90 minutes, lid slightly open. Stir and scrape halfway through. Your onions should be soft and a deep golden brown.
- Take it out and throw it back on the stovetop. Cook those onions on medium heat until they brown and a crust forms on the bottom of the pan. This takes about 30 minutes. Keep stirring and scraping.
- Now, stir in water, 1/4 cup at a time, scraping off that crust until it evaporates and forms again. Do this 3-4 times until your onions are dark brown.
- Stir in the wine and cook until it evaporates, about 5-7 minutes.
- Add in the chicken and beef broth, more water, thyme, bay leaf, and 1/2 teaspoon of salt. Bring it all to a simmer.
- Reduce the heat to low and let it simmer for 30-40 minutes.
- While that’s happening, crank your oven up to 425 and roast those marrow bones for 15 minutes. Season them with some salt and thyme.
- While the marrow is roasting, toss your slices of bread in the oven for 5-7 minutes to get them all toasty.
- Take the marrow bones out and let them cool.
- Get 8 oven-safe bowls, place them on a baking sheet, fill them with the soup, and top each with toasted bread slices and raclette.
- Switch your oven to broil and, with the top of the bowls 6-8 inches below the broiler, broil until the cheese is all gooey and melted. It takes about 5 minutes.
- Serve it up with the bone marrow on the side and sprinkle it with fresh thyme leaves and flaky salt. You can spoon the bone marrow on top of the bread or mix it into the soup, depending on what you fancy. (We love it on top of the bread.)
Girl Carnivore Expert Recipe Tips
With a soup as simple as French Onion, splurge on quality ingredients like beef bone broth for this as the beef broth for this. We wanted a rich, robust flavor and knew that it wouldn’t come from our standard broths.
And then, we turned things up a notch by infusing the buttery bone marrow into this soup. We roasted it on the side and let people pick if they swirled it into the hot soup or spread it over slices of homemade bread.
CARAMELIZE YOUR ONIONS FOR FRENCH ONION SOUP
Be sure to allow the onions to caramelize. This is part of the flavor-building process. Sure, you can rush it and have soup faster, but the flavor from the slowly caramelized onions really is the foundation for this spectacular recipe.
In this case, you not once, not twice, but three times cook the onions. First, the onions are baked and then seared a bit on the stovetop. Finally, the onions sweeten just a bit more in the rich hot broth.
This is like the essence of French cooking, so calling it “French Onion” makes sense. Simple things are made vastly complex and interesting by transforming them via simple techniques. Voila! (Which is French for “Now ain’t that tastier than a spoonful of rainbows?“)
Leftovers & Reheating
If you follow the directions for this recipe, you will make a LOT of soup. And, as much as the broth was amazing, even we had too many leftovers.
Store leftover soup in an airtight container in the fridge for 3–4 days. Reheat just what you need in a pot or Dutch oven.
To freeze leftover French onion soup: Pour cooled soup into resealable freezer bags. Try to portion them into 2 bowl servings. Make sure to label them before the soup goes in, with the name of the recipe and the date for better freezer organization. Then, lay them flat on a baking sheet and place them in the freezer.
Once frozen in flat layers, they can be stored in the freezer for 3 to 6 months.
One spoonful of this simple soup will warm you up like a good hug. With simple ingredients and a depth of flavor, this Bone Marrow French Onion Soup transforms a classic into a carnivorous delight.
Have you tried this recipe? Do us a favor and rate the recipe card with the ⭐ ⭐ ⭐ ⭐ ⭐ and drop a comment to help out the next reader.
French Onion Soup with Bone Marrow
- Preheat oven to 400 degrees
- Heat a 7 quart or larger dutch oven on low (seriously, you need a pot this big, it makes a ton!) and melt butter.
- Remove from heat and stir in onions and 1 tsp salt so that onions are coated.
- Transfer Dutch Oven to lower center rack in oven, and cook covered for 1 hour.
- Remove from oven and stir, scraping bottom and sides of pot.
- Return to oven for 90 minutes with lid slightly ajar. Stir and scrape again half way through. (Onions should be very soft and golden brown.
- Remove from oven and transfer to stovetop.
- On medium heat, cook onions until they brown and a crust forms on the bottom of the pan (about 30 minutes) stirring frequently and scraping the pan as you go.
- Stir in water, 1/4 cup at a time scraping free crust, until it evaporates and crust reforms on pan. Repeat 3-4 times until onions are very dark brown.
- Stir in wine and cook until evaporated (5-7 minutes)
- Stir in chicken and beef broth, water, thyme, bay leaf and 1/2 tsp salt and bring to a simmer.
- Reduce heat to low and simmer 30-40 minutes.
- meanwhile, set oven to 425 and roast marrow bones 15 minutes, seasoned with salt and thyme.
- while marrow is roasting, toast your slices of bread in the oven for 5-7 minutes
- Remove marrow from oven and let cool.
- Place 8 oven safe bowls on a baking sheet, fill with soup and top each with a slice of bread and raclette.
- Switch oven to broil and with the top of the bowls 6-8″ below broiler, broil until cheese is melted (approximately 5 minutes).
- Serve with bone marrow on the side. The marrow can be spooned on top of the bread, or mixed into the soup per individual preference (I think it is delicious on top of the bread) follow link for the full marrow recipe.
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Before we even get to the recipe, we need to discuss that onions are not all the same. This recipe calls for 4 pounds of onions, and although we had a few pounds of yellow onions on hand, we also threw in 2 Vidalia onions just to sweeten things up.
For the soup, though, we wouldn’t use 4 pounds of sweet onions though. You want a good, bold but not harsh or bitter flavor. For French Onion Soup, that is classic yellow onions. They cook down beautifully and are the perfect base for this.
If you like beef stock style soups, by the way, then you might also want to check out this beef and potato soup too…
Raclette is a wheel of semi-hard cheese with a slightly nutty bite to it. Think Swiss Cheese but without the holes and not quite as tangy. It melts nicely, so it works particularly well for the top.
If you can’t get raclette, there are plenty of similar cheeses to choose from. Gruyere cheese is very often the cheese of choice for a substitute to raclette, but you can also do Emmentaler, Jarlsberg, or Parmesan as well. The semi-hard cheeses are ideal since they get a good melt going.
Absolutely! While the recipe uses a large pot, you can adapt it to a slow cooker for convenience. Just follow the same steps, transferring everything to your slow cooker and letting it simmer on low for 6-8 hours.
Yes! If you prefer not to use wine, you can substitute it with additional chicken stock for a non-alcoholic version.
Go for a dry red wine like Cabernet Sauvignon or Merlot. These types blend well with the rich flavors of the soup without making it too sweet. If you don’t have red wine, a dry white wine, like Sauvignon Blanc, can do the trick.
While bone marrow enhances the richness of the soup, you can still make a delicious French onion soup without it. The broth will have a robust flavor from the caramelized onions and other ingredients.