French Onion Grilled Cheese Sandwich

Every once in a while I get a hankering for something gooey, melty and cheesy. No, it’s probably not the healthiest, but somehow I feel comfort food, on occasion, is well deserved, if not completely warranted. Last Sunday, all I wanted to do was plop on the couch, put my feet up and devour this decedent grilled cheese sandwich. Flavorful, nutty Gruyere cheese is melted over onions that are caramelized long and slow, prepared like traditional French Onion Soup. The process of caramelizing the onions brings out their delicious complexity and sweetness. I prefer to use a wholesome, whole grain bread- homemade if possible, but in a pinch, store bought french bread works great too. Serve this with a mesclun salad, dressed with a light Dijon vinaigrette and enjoy the luscious flavors and textures.

The season of  alliums has begun. Farmers markets are filled with all different varieties, and as the season progresses, more and more will become available. Right now look for sweet onions, chives, ramps, garlic scapes…..and one of my new favorites – green garlic. ( Recipe coming soon).

I have a confession to make- this good looking bread comes from Trader Joes. I hesitate to tell you this because 1. it’s store bought and not homemade,  2. it’s not locally made- and we do have awesome locally made bread- my favorites being here and here, which taste better, but require an extra trip to pick up – so, in a pinch, this bread at Trader Joe’s fits the bill. It’s very easy to miss… but you’ll know it because comes in half loaves, on the bottom shelf.  It looks dry, but it’s surprisingly not. 
Gruyere was always the cheese that was too expensive and luxurious to buy in my younger years. These days, I spurge on occasion, when I know it will make a real difference. You could substitute another cheese, but it wouldn’t be quite as good. Gruyere is earthy, complex and nutty, with the perfect balance of sweetness and saltiness, pairing perfectly with the caramelized onions. For the full flavored experience, splurge a little and try Gruyere. It will rock your world. The smell alone, of Gruyere melting in your kitchen, is worth the extra expense. And can turn a grumpy husband into a kitten. 
For this recipe, make sure to buy Gruyere that is young and softer, rather than aged…which will be hard with visible cracks.

The easiest way to caramelize onions is to use your biggest heavy bottom skillet, set a burner to medium low heat, and let the pungent alliums cook long and slow in a little oil or butter. Stir every once in a while, but feel free to leave them and attend to other things. At this temperature, the moisture releases and the sugars caramelize steadily, never burning but growing ever more golden and delicious. At the end, add a pinch of salt and pepper and perhaps a splash of port, sherry or beef stock if you like, letting it cook off. This is the essence of French onion soup.

Butter the outside of the bread. I like adding a whole grain mustard to the insides of the bread for a little bite. Layer the bread with grated Gruyere, then a generous amount of  caramelized onions, then more Gruyere, and top with the other slice of bread.

Heat oil, butter or a combination of both ( my preference)  in a large oven proof skillet, over medium heat. Toast both sides of the sandwich until perfectly golden brown and place in a 350F oven until the cheese is nice and melty. 
Cut in half and serve with mesclun salad. 

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 French Onion Soup Grilled Cheese Sandwich
by June-7-2014
A grilled cheese sandwich with Gruyere and caramelized onions

1 large red or yellow onion- thinly sliced about 1/8 in thick
1 T oil
pinch salt
pinch fresh cracked pepper
1/4 C sherry, port, or beef stock ( all optional)
4 slices hearty Bread or French Bread
2 T Butter ( or half oil)
1 C grated Gruyere cheese
1 tsp fresh thyme ( optional) 
Whole grain Mustard ( optional)
In a large heavy bottom skillet, or cast iron pan, heat oil on medium heat. Add onion and saute for 5 minutes, stirring to coat. Turn heat down to medium low. Stir occasionally and continue sauteing for 30 minutes. Onions will sweat out their moisture, and eventually caramelize into a golden brown. Add a generous pinch of salt, a splash of port, sherry, or stock (optional) and let the liquid cook off. Remove from pan and wipe it out with a paper towel, to use again.  
Preheat oven to 350 F
Spread outer  slices of  bread with softened butter. Spread inside with whole grain mustard (optional) On two slices, divide and layer shredded Gruyere, top with caramelized onions, sprinkle with fresh thyme leaves, then add the rest of the cheese. “Close” the sandwiches with the other slices of bread, and gently press together
Heat 2 butter (or a combination of butter and oil) in the same skillet over medium heat. Place sandwiches in the pan and toast, carefully flipping when golden brown and cheese begins to melt. Place in a warm oven to fully melt the cheese if necessary, which will preventing the bread from getting too dark. Cut in half and enjoy.

Prep time: Cook time: Total time: Yield: 2

thanks for sharing!
thanks for sharing!


  1. says

    This looks so delicious. True, comfort food may not always be the healthiest, but it’s good for your SOUL. And as long as you’re using good ingredients (which you obviously are) the result will always be excellent!

  2. Anonymous says

    Yum Yum! Might I add a side of home made apple sauce for dipping this marvelous concoction to honor my dear German daddy! Done!

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