Caramelized Onion and Mushroom Grilled Cheese

February 27, 2013

There are very few things that every time I try to cook result in complete failure: a simple grilled cheese is at the top of that list.  I’m not sure what it is about having two slices of bread and one slice of cheese that becomes so intimidating for me, but I either somehow melt the cheese into the bread so there’s no visible cheese remaining, burn the outside of the bread until it’s inedible, or a combination of the two.  Luckily, Josh is a grilled cheese master – carefully and lovingly flipping the sandwich to perfection.


Good news is that if you make the sandwich at all more complicated, say add some veggie bacon or a slice of tomato, and I’m back on top.  Bonus points if I make it on a waffle iron (if you’ve never made a grilled cheese on a cheap, regular waffled iron go do it NOW!!  I’ll be here when you get back).


I’m one of those weirdos that has liked onions and mushroom for as long as I can remember.  I was craving a big pile of both the other day and thought that wasn’t a socially acceptable dinner, so I slapped it on a grilled cheese and had the most delectable sandwich I’ve had in a long time!  Feel free to play around with the bread and cheese choices.  I thought rye bread would be amazing too, but then I would’ve been too tempted to smother it in thousand island dressing, Reuben style.

Caramelized Onion and Mushroom Grilled Cheese

  • 1 onion
  • 3 cloves garlic
  • 6 oz baby bella mushroom or other mild mushroom (about 6 medium mushrooms)
  • ¾ c white wine
  • Salt and pepper to taste
  • 2 slices Swiss cheese
  • 4 slices sourdough bread (or GF bread)
  • Butter, olive oil, nonstick spray (optional, pick at least one)

  1. Slice the onion in half and then into half circles. Mince garlic and roughly chop mushrooms.
  2. Place a nonstick pan over medium-high heat. Add butter, olive oil, or a spritz of nonstick spray and add the onions. Let sit for a minute or so before stirring and turn the heat down to medium. Add the garlic and stir frequently. The onions should begin to turn slightly brown. Add the mushrooms and cook until soft.
  3. Add splashes of wine and scrape the bottom of the pan to get any stuck onion bits. Wine will quickly evaporate off, but add small amounts at a time and stir to coat onions and mushrooms very well.
  4. Once onions have a nice brown color (took me ~ 15 minutes), remove from heat and place in a bowl. Wipe out pan and place back over medium heat.
  5. Assemble 2 sandwiches with onion mixture and Swiss cheese. Using butter, olive oil, or nonstick spray grill in pan until bread is brown and crispy.
  6. I like to place my sandwiches in a low heat oven for a few minutes to get the cheese extra melty.

The nutritional facts don’t include bread, as breads vary pretty widely in calories. For a vegan sandwich, skip the cheese and add zucchini and eggplant.

Nutrition Information
Calories: 150 Fat: 7g Carbohydrates: 12g Fiber: 2g Protein: 11g


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    Amy Lou Sep 14, 2013

    Gooeylicious! First time making a grilled swiss cheese with onions and mushroom. Opted the white wine since I didnt have it on hand. Still taste delicious without it. Made it as my dinner. Never thought this would be so simple to make that tastes so good. Will make again and again. Thanks!

      Kelly Sep 14, 2013

      Glad you liked it, Amy!

    marcie@flavorthemoments Mar 01, 2013

    This looks so delicious! I love french onion soup….this is kind of like the grilled cheese version. I’ve got to try this.

      Kelly Mar 01, 2013

      I’ve actually never had french onion soup– if this is what it tastes like, I need to find a good recipe ASAP!

    Erin | The Law Student's Wife Feb 28, 2013

    Caramelized onions = candy. Love the nice brown color you got on the bread too. Grilled cheese for grown ups. It never gets old!

    Anna @ ApronHearts Feb 28, 2013

    Yum, yum!!! Grilled to perfection and filled with all the good stuff. So nice that you used sourdough bread for this.

    Joanne Feb 28, 2013

    Well I think you’ve gotten past your grilled cheese struggles but this looks amazing!

    Sara {Home is Where the Cookies Are} Feb 28, 2013

    Oh yum, YUM! Love mushrooms, and love grilled cheese. Such a guilty and WONDERFUL indulgence!! Your mushrooms look a lot like some that we use for pizza toppers, and omelette fillers, and eat-out-of-the-pan-ers. It’s the wine and the garlic – gets us every time! Looks divine!

    sally @ sallys baking addiction Feb 27, 2013

    I wish I could have this for dinner right now instead of my boring salad. WOW. It looks AMAZING! I love finding interesting and unique grilled cheese recipes. 🙂

    Julia Feb 27, 2013

    I could eat caramelized onions by themselves, they’re so tasty…put them on toasty bread with melty cheese and I’m swooning! Will definitely be making this gem of a sandwich!

    Ashley Bee Feb 27, 2013

    I love unique grilled cheese 🙂 This looks delicious!

    Rachel @ Bakerita Feb 27, 2013

    Oh my goodness this looks amazing!! Such perfect veggies to put into a grilled cheese.

      Kelly Feb 27, 2013

      I can’t believe anyone could ever not love mushrooms 😉

    crazyforcrust Feb 27, 2013

    This sounds amazing. My husband and I would both be addicted to it!

      Kelly Feb 27, 2013

      I pretty much am. I made the mistake of looking at the pictures again after this posted, and now all I can think about is mushroom-oniony goodness.

    Natalie Feb 27, 2013

    I am drooling over this photo! Mushroom and onion and cheese are like the best combo ever!