French Onion Grilled Cheese Recipe (2024)

By Ali Slagle

French Onion Grilled Cheese Recipe (1)

Total Time
45 minutes
Read community notes

Grilled cheese is a near-perfect food on its own, but adding bacon, kimchi or, in this case, heaps of caramelized onions really makes it special. Caramelizing onions takes a good half-hour, so save this recipe for when you have a little extra time and company (this recipe serves two). If time permits, you could even prep them ahead in a slow cooker. Rather than layer the grated Gruyère and the warm caramelized onions in the sandwich, you should stir them together before assembling, which guarantees that the cheese will melt evenly throughout and that each bite will contain the perfect ratio of fragrant cheese to jammy onions. A splash of sherry, red-wine or white-wine vinegar added to the onions balances out the buttery flavors, but a side salad dressed with a tangy mustard vinaigrette would do the trick, too. (Watch the video of Ali Slagle making French onion grilled cheese here.)

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Yield:2 servings

  • 4tablespoons unsalted butter
  • 1pound yellow or Vidalia onions, peeled, halved and thinly sliced
  • Kosher salt and black pepper
  • 2teaspoons sherry, red-wine or white-wine vinegar (optional)
  • 4ounces Gruyère cheese, grated
  • 4slices bread, cut no wider than ½-inch thick

Ingredient Substitution Guide

Nutritional analysis per serving (2 servings)

680 calories; 44 grams fat; 25 grams saturated fat; 0 grams trans fat; 13 grams monounsaturated fat; 3 grams polyunsaturated fat; 46 grams carbohydrates; 5 grams dietary fiber; 15 grams sugars; 25 grams protein; 874 milligrams sodium

Note: The information shown is Edamam’s estimate based on available ingredients and preparation. It should not be considered a substitute for a professional nutritionist’s advice.

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French Onion Grilled Cheese Recipe (2)


Make the recipe with us

  1. In a large skillet over medium-high heat, melt 2 tablespoons butter. Add the onions and season with salt and pepper. Cover and cook, stirring once or twice, until the onions are softened, 3 to 5 minutes. Uncover, reduce the heat to medium-low, and cook, stirring occasionally, until deep golden brown, 20 to 25 minutes. If the onions look dry or like they might burn, add a few tablespoons of water at a time, scraping up any browned bits that are stuck to the bottom of the skillet. If desired, once the onions are done, deglaze the skillet with vinegar and cook until the liquid has evaporated, about 1 minute. Transfer the onions to a medium bowl and season to taste with salt and pepper. Wipe out the skillet, or wash it, if necessary.

  2. Step


    Add the cheese to the onions and stir to combine. Put down two slices of bread, and scoop half of the cheese-onion mixture onto each one. Top with the remaining slices of bread, and press down gently.

  3. Step


    In the skillet, melt 1 tablespoon butter over medium heat. Add the sandwiches and cook until the bottoms turn golden brown, 3 to 4 minutes, reducing the heat to prevent toast from darkening too quickly, if needed. Add the remaining 1 tablespoon butter, flip the sandwiches, press down and cook until the cheese has fully melted and the bottoms turn golden brown, 3 to 4 minutes. Serve immediately.



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Cooking Notes


Caramelized onions freeze well. After I harvest onions in the early fall, I set up a table next to my gas grill. I put a big skillet on the side burner, add some oil. I cut up three pounds of so at a time and toss them in the skillet. Doing it on a breezy day keep the tears and smell at bay. After several batches, I let the caramelized onions cool and fill snack size Ziploc bags. Three bags fit into a quart freezer bag. They keep all winter.


A friend pointed this recipe out the other day and it fit the bill for a perfect, Lenten Friday, lunch. The wife approved with double thumbs up. My one tweak: I deglazed the pan with some bourbon. It's something I usually do if I am caramelizing onions. It's adds a nice vanilla sweetness.


Made these with homemade tomato soup and thought they were great. We had leftovers, so I made myself another soup and sandwich, but added some minced fresh dates to the onion and heated them again in a little butter. Wow! The very slight bitterness of onions was transformed. The added specs of sweetness to the combination of crisp bread, silky melted cheese and savory onions elevated this already excellent sandwich to something REALLY special. Give it a try. You’ll like it.


As Natalie notes, getting the water out is essential for caramelization. One trick I learnt from another commenter on another recipe is to spread your sliced onions on a plate, cover with a paper towel, and zap in the microwave for two minutes. Doing so takes some of the moisture out of the onions and reduces the time needed for caramelizing.


I love Ali Slagle's recipes, and I love caramelized onions, so what a great combination on a cool, rainy, early spring weekend afternoon. Deglazing the pan with sherry vinegar took this dish over the top, as did some leftover Emmi Roth Le Maréchal cheese. Genuine comfort food, and easy to make, too. I can easily imagine making this on a weeknight. Whole Foods' "bits and pieces" of leftover ends of cheese make it possible to purchase just a small bit of some really interesting cheese.


I love making this if I have the time to caramelize the onions. My super lazy version of this is to buy a good onion jam, and spread that inside the sandwich with a good cheese.


Try buttering the bread instead of the pan. Does a better job of getting the butter right where you want it.


I make my carmelized onions in my Instant Pot. It takes about the same time as using a skillet, but it doesn’t have to be watched and stirred. I put 1-2T each of butter and olive oil in pot on sauté, add 2-3 lbs sliced onions and sauté until onions are coated, the pressure cook for 25 minutes. Quick release then sauté again until liquid has evaporated (5 min+-) and the onions are golden. No burning and very easy.


I live in Russia and real Gruyere is hard to find and crazy expensive here, so I used some not so fancy cheese and common onions (we don't have varieties sold at stores) — still turned out super delicious and super French. It's amazing how 20 minutes of cooking in butter can transform the texture of onions and make them a sophisticated dish.


I realized that I didn't have bread but did have corn tortillas- so this became a DELICIOUS quesadilla.


My husband grills the bread slices on both sides on a buttered griddle first, then adds the cheese to one and puts the second slice on top of the first. This way the bread is good and crispy outside and inside but still moist inside (don’t overdo it). We also add different types of cheese. Best GC I’ve ever eaten!


Used Publix (sorry New Yorkers its a Florida thing) Five Grain Italian bread and a well seasoned cast-iron skillet. Mixing the grated cheese in with the caramelized onions before spreading on the bread is genius. 10/7 will make again.


Added balsamic vinegar to the caramelized onions. Used a thin layer of mayo to cook the sandwich which made the bread golden and perfectly crisped. I had extra cheddar and American in my frig, which I added. I'm staying home to help 'flatten the curve' - this sandwich was like a warm hug. Since I can't have human contact this was a good substitute.


Just FYI, many experts caution against trying to caramelize sweet onions (like Videlias). I don’t know why they say this (having been cautioned, I’ve never tried to do that), but cheap yellow onions caramelize beautifully.


The "bits and pieces" suggestion is a great way to keep this meal from costing a fortune or having to figure out what to do with a bunch of gruyere. I may try fig pieces added in or fig balsamic to deglaze.


This is amazing. When I deglazed the onions with vinegar I added a bit of worcestershire sauce as well. Sublime.


These were absolutely delicious. I’ll be making these regularly.


As others have said, caramelizing the onions takes longer than 1/2 hour, so plan accordingly. I took the advice to make more, and I’m freezing the rest. I used sourdough bread, and the sandwiches came out well. My husband loved them. Surprisingly, they were a bit rich for me, so I have mixed feelings about this recipe.

Chef Carl

I prepared this original recipe several times, always to rave reviews. For a recent theme party, I added cumin, cilantro, bell peppers,and jalapenos to the onions. I replaced the Gruyere with a blend of grated Oaxaca and Chihuahua cheese. I used a flour tortilla and made it into a quesadilla, and served it with a chicken tortilla soup.


So good. The onions and cheese make it hard to hold together and when you cut or bite into it, it all gushes out, but the taste is amazing. They're not kidding to err on the side of making too many onions than not enough.

Susan Soroka

Best grilled cheese sandwich I ever cooked and ate! Slicing the onions thin allowed them to carmalize beautifully. I made enough for just one sandwich but do have left over cheese/onion mixture! I used 1 yellow onion, 3.5 oz container of grated gruyere, tsp1 red wine vinegar, and the amounts of butter as written in recipe. Didn't resalt cheese/onion mixture as suggested at the last of Step 1. Great recipe!


Excellent and fairly easy, so long as you have the patience to caramelize the onions properly.I found that this made more filling than two sandwiches could hold, which isn't necessarily a problem but worth noting. On a second attempt I deglazed the pan with cognac instead of vinegar, and it brought a nice mellow flavor that I think fits the recipe well.


Combining cheese + onions is brilliant. This was easy and delicious, along with tomato soup on a cold winter night.


These were very good, but next time I would use a stronger flavored cheese.

Debbbie D

Twenty-five minutes of caramelizing onions allowing time for doing the dishes, prepping the next morning's coffee and feeding dear pup, all while getting lost listening to a book. They're done in no time. Delicious sandwich on a freezing late afternoon Saturday in January.


Can’t spend this much on cheese for 2 sandwiches, what else besides Gruyère?


After reading notes I did these and this recipe has now became my wife’s favorite— I butter the bread directly on both sides (not too much butter on one side that goes to the pan where it was cooked) and I use Trader Joe’s shredded Gruyère and Swiss mix- it tastes so heavenly good.One time I thought the recipe calls for garlic so I added it to the onions - still tasted good. Deglazing the pan with red wine vinegar is a must. I’m actually cooking it tonight and I plan to try it with sherry.

M. Feliciano

Followed the recipe. Quite delish. Next time, I might modify the amount of onions (decrease slightly) and the cheese (increase slightly). Might also add a bit of fresh thyme to the mix. Definitely adding to the winter repertoire.

Sue Hagar

Excellent! The only tweet I made is buttering the bread instead of adding butter to the pan. Like someone mentioned in an earlier post, it gets the buttery toastiness where you want it.

Lori Lewis

You will remember this sandwich forever. The BEST grilled cheese you'll ever have.

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French Onion Grilled Cheese Recipe (2024)
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