Love french onion soup? I think you're going to love it even more in grilled cheese form! This French Onion Grilled Cheese takes perfectly caramelized onions and sandwiches them between two slices of buttery bread with fresh thyme and lots of melted gruyere cheese.
(This recipe was originally published in August 2014, but was updated with new content and photos in 2021).
Today I put soup in a sandwich and am sharing the recipe with you now. OK, so I didn’t literally take a bowl of soup and spoon it into a sandwich.
But I did take my all-time favorite soup and combine it with my all-time favorite sandwich: French onion soup and the mighty grilled cheese sandwich.
When I was a kid, I would have eaten a bowl of french onion soup and a caesar salad every single night for dinner if I had the choice.
Every restaurant we went to, I eschewed the kids’ menu and asked to order two appetizers. My sodium-intake was probably out the roof, but I was happy.
I probably would have been even happier if that soup came in sandwich form. Because who on Earth chooses to eat a bowl of soup over a grilled cheese?
Oh, and I've already made it in pizza form!
How to Caramelize Onions
As with most grilled cheeses, this sandwich is easy to make. But it does require a little bit of time since caramelizing onions requires time.
And they're so, so worth it. Even if you think you don't like onions, I have a feeling that once you try them caramelized, you will be changing your tune. Especially if they're made into a grilled cheese!
To caramelize onions, start by placing a large skillet over medium heat and adding olive oil and 2 Tbsp butter.
Once butter is melted, add in onion slices, sprinkle with salt and pepper, and cook for about 5 minutes, stirring frequently.
It looks like a lot of onions for two sandwiches, but trust me, they are going to shrink down dramatically!
After 5 minutes, turn heat to low, add brown sugar and apple cider vinegar and stir occasionally as onions begin to brown.
Continue to cook and stir occasionally until onions are browned to your liking. Caramelization process will likely take at least 30 minutes total.
Before removing skillet from heat, stir in thyme.
How to Make French Onion Grilled Cheese
Now that your onions are beautifully caramelized, you're ready to assemble your grilled cheese sandwiches.
Spread butter on one side of each bread slice.
Place a few slices of gruyere cheese on two of the bread slices (the unbuttered sides).
Pile caramelized onions on top of cheese.
Add remaining cheese slices to the top of the onions.
Place remaining slices of bread on top, buttered sides facing out.
Heat a large skillet or griddle over medium-low heat (if you want to use the same skillet you just cooked the onions in, you can) and place sandwiches on skillet.
Let cook for about 2 minutes before flipping sandwich and cooking for another 2 minutes on the other side, until bread is golden and cheese is melty.
Remove from skillet and slice sandwiches in half before serving.
Like I said, even if you don't generally like onions, I implore you to try this sandwich!
My husband is one of those people who said he didn’t really want to try this because it involved so many onions.
Then he tried a bite and then had another. And another. And then a whole french onion grilled cheese was gone. Because nobody can resist caramelized onions!
If you’re still uncertain, combine them with slightly salty cheese and crispy bread and then come back and talk to me.
And if you're a fan of french onion soup? You are going to go absolutely wild for this grilled cheese sandwich!
It's like the soup with melty gruyere cheese is on the outside and the crispy buttery croutons are on the outside.
AKA my idea of heaven. Give me a side of Caesar salad and call it a meal my preteen self would order every single time she went out.
More Grilled Cheese Recipes
If you still don't think onions are your thing OR you just want more ways to enjoy grilled cheese (I could legit eat one every day), I have plenty of recipes for you.
Here are some of my favorite grilled cheese recipes:
- Caprese Grilled Cheese
- Greek Grilled Cheese
- Jalapeño Popper Grilled Cheese
- Brie Grilled Cheese with Fig Spread, Green Apple, and Prosciutto
- Brussels Sprouts and Cranberry Relish Grilled Cheese
- Buffalo Chicken Grilled Cheese
- Cinnamon Sugar Brie and Apple Grilled Cheese
- Antipasta Grilled Cheese (from Spiced Blog)
- Lobster Grilled Cheese (from Jenny Shea Rawn)
We all know that grilled cheese is the perfect complement to soup... But now I can't stop thinking about more soups AS grilled cheese sandwiches.
And with that said... How do you think a chicken noodle soup sandwich would be?
What kind of soup would you love to eat in sandwich form?
French Onion Grilled Cheese
Ingredients
- 2 Tbsp olive oil
- 3 Tbsp unsalted butter, divided
- 2 large vidalia onions (or other sweet onions), sliced thinly
- ¼ tsp salt
- ¼ tsp pepper
- 2 Tbsp brown sugar
- 1 Tbsp apple cider vinegar
- ¼ tsp finely chopped thyme
- 4 slices good crusty bread
- 3 oz. gruyere cheese, thinly sliced
Instructions
- Place large skillet over medium heat and add olive oil and 2 Tbsp butter.
- Once butter is melted, add in onion slices, sprinkle with salt and pepper, and cook for about 5 minutes, stirring frequently.
- After 5 minutes, turn heat to low, add brown sugar and apple cider vinegar and stir occasionally as onions begin to brown.
- Continue to cook, stirring occasionally until onions are browned to your liking. Caramelization process will likely take at least 30 minutes total. Before removing skillet from heat, stir in thyme.
- Once onions are caramelized, spread remaining Tbsp butter on one side of each bread slice.
- Place a few slices of cheese on two of the bread slices (the unbuttered sides). Pile caramelized onions on top of cheese and add remaining cheese slices to the top of the onions. Place remaining slices of bread on top, buttered sides facing out.
- Heat a large skillet or griddle over medium-low heat (if you want to use the same skillet you just cooked the onions in, you can) and place sandwiches on skillet.
- Let cook for about 2 minutes before flipping sandwich and cooking for another 2 minutes on the other side, until bread is golden and cheese is melty.
- Remove from skillet and slice sandwiches in half before serving.
Lauren at Keep It Sweet says
I agree - I'm not a fan of raw onions but caramelized onions are freaking amazing. And this sandwich looks like the perfect comfort food to have on repeat:-)
Emily aka The Three Bite Rule says
Yum! Great idea! I did something similar a long time but got impatient on the onions so I doused them in balsamic vinegar, which ended up being strong, but tasty. These would be fun open faced, as crustini too!
Bianca @ Confessions of a Chocoholic says
I'd like this sandwich for breakfast please.
Rachel says
Um...WOW! I love French Onion soup AND grilled cheese. I wish I had this for lunch today...
Leah | So, How's It Taste? says
What a fantastic idea for a sandwich! I'm a big french onion soup lover and would devour this! I'm with ya on the caramelized onions...everyone should love those!
Monique says
soup... hmmm. maybe a stew. Lets do a beef stew sandwich with sharp cheddar cheese.
This looks awesome. and while we are on the subject, lets figure out this grilled cheese soup thing... I think it would work. But only a shot glass because thinking about drinking a buttery melty gooey bowl of cheese soup will probably kill me.
sarah k @ the pajama chef says
this is totally genius! love it.
Odetta says
Best idea on earth! I want to dig right in!
Asmita says
So yummy!
Tandy | Lavender and Lime says
I am salivating at the thought of trying this! I love caramelized onions! If I could recreate a tomato soup in a sandwich form I would do so 🙂
Justine says
Yum!!! Always in the mood for something like this!
Alyssa @ My Sequined Life says
OOOH this sandwich looks perfect! I LOOOVE french onion soup and I love grilled cheese (obviously), so this is blowing my mind. Seriously - what a great idea, Sues! Checking out the recipe on Parade now!
Megan says
I would definitely love French onion soup as a sandwich. It has all the components already… so perfect! It might be fun to do a broccoli cheese soup sandwich.
Pam says
Oh my. These beauties have me literally drooling.
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Monet says
Yep. I loved French Onion Soup and still do. You may have just made my favorite even better!
Joanne says
Agreed that caramelized onions are nothing like raw onions! And I love this cheesy sandwich take on French onion soup. Swooning, in fact.
Ashley @ QLCC says
This looks amazing. I miss grilled cheese, I need to make some soon.
bellini says
Now here's a new idea I can gravitate towards. Who can resist that cheese an this onions.
Laura Adams says
Just saw a variation of this on the Food Network's "The Best Thing I Ever Ate: Appetizers". It was at a swanky restaurant, and they served the French Onion 'Soup' in little dumplings on a bed of melted Gruyere . I think you're on to something!
Victoria says
Love this concept! French onion soup is my favorite soup, and making it into a sandwich is brilliant 🙂 yum!!