Caramelized Onion, Spinach, and Avocado Quesadillas

Caramelized Onion, Spinach, and Avocado Quesadillas
An avocado a day keeps the doctor away. Okay, that statement may need some fact-checking, but I do eat a whole avocado most days — so I’ve made it my motto as well as my M.O. Adding avocado to a hot, melty quesadilla may seem strange, but let me assure you: it just works. For these Caramelized Onion, Spinach, and Avocado Quesadillas, you simply add the sliced avocado at the very end of the cooking process so it doesn’t get overly hot or mushy.

Caramelized Onion, Spinach, and Avocado Quesadilla
Caramelized onions definitely take their fair share of time to cook, but they’re so worth it. They add rich, deep flavor to a meal, which makes you feel fancy — even though you secretly know they’re a cinch to make. The onions cook down quite a bit, so I use two for this recipe. To caramelize them, start by adding 3 to 4 tablespoons of oil to a skillet, add the onions, and sauté over medium heat. The onions will sweat, then turn translucent, and then finally brown into caramelized goodness. The best thing about caramelized onions is that they freeze well! So you can make a big batch when you have time, keep ‘em in the freezer, and use them whenever you need an emergency quesadilla.

Those sweet caramelized onions paired with creamy avocado make a delicious quesadilla on their own, but we also invite spinach, because: vitamins. Since everything on the inside of this quesadilla is soft, I like to make the tortilla crispy to add contrast. I cook the quesadilla on medium-low heat for a few minutes so that the tortilla crisps up nicely, but doesn’t burn. Who would have thought all you need for a fancy, flavorful quesadilla is onion, spinach, and avocado?

Enjoy this crispy/creamy quesadilla with your favorite salsa or cilantro pesto.

Caramelized Onion, Spinach, and Avocado Quesadillas

Prep Time: 5 minutes

Cook Time: 1 hour

Total Time: 1 hour, 5 minutes

Yield: 4 quesadillas

Serving Size: 1 quesadilla

Caramelized Onion, Spinach, and Avocado Quesadillas

Creamy avocado, sweet caramelized onions, vitamin-packed spinach, and Jack cheese melt together in a crispy golden-brown tortilla.


  • 3 tablespoons grapeseed oil or olive oil
  • 2 large yellow onions, halved and sliced
  • 1/2 teaspoon salt
  • 10 ounces baby spinach
  • 2 cups shredded Monterey jack cheese
  • 2 avocados, pitted, peeled, and sliced
  • 4 large flour tortillas


  1. Add the oil to a large sauté pan over medium heat. Add the onions and salt and cook, stirring occasionally, until the onions are soft and deep golden brown, about 30 to 40 minutes. (If the sides of the onions begin cooking too fast, lower the heat to medium-low, add a little more oil, and stir. Your goal is to have the onion slices cook as uniformly as possible.) Remove the onions from the pan and place them in a bowl.
  2. In the same sauté pan over low heat, add the spinach and cook, stirring frequently, until wilted, about 2 minutes. Remove from heat and transfer the spinach to another bowl, then carefully wipe the pan dry with a paper towel.
  3. Return the pan to the stove and increase the heat to medium-low. Lay one tortilla flat in the pan. Evenly sprinkle 1/2 cup of cheese over the top. To the bottom half of the tortilla, add 1/4 of the caramelized onions, followed by 1/4 of the wilted spinach. Heat until the cheese melts and the tortilla is browned and crispy.
  4. Add the avocado slices (about 1/2 of an avocado per quesadilla), and immediately fold the tortilla in half, onto itself, and flip it over. Continue cooking for about 30 seconds or until warmed through.
  5. Using a spatula, transfer the quesadilla to a cutting board. Cut into fourths. Repeat this process with the remaining ingredients and serve with your favorite salsa or cilantro pesto.

About Julia

Julia Mueller writes the food blog, The Roasted Root, and is the author of Delicious Probiotic Drinks and Let Them Eat Kale!. A Lake Tahoe native, Julia loves to play outdoors, and enjoys developing recipes that are nutrient-dense and approachable to make any night of the week.   Read more from Julia →

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  1. says

    Yum! This part made me laugh: “…use them whenever you need an emergency quesadilla”. I’ve got extra batteries, candles, and caramelized onions and quesadillas! :)
    Love the addition of spinach, and that you made the whole thing crispy! Who wants a mushy quesadilla?

    • Julia Mueller says

      Glad you love the idea of spare caramelized onions as much as we do! They really are amazing for injecting lots of flavor into a meal. Hope you enjoy the quesadilla!

  2. Kat says

    Caramelized onions are one of my favorite things, so I will definitely make this! I never knew you could make them ahead of time and freeze them. How do you recommend reheating them? Just throw the frozen onions in the skillet for a bit?

    • Julia Mueller says

      So glad to hear you’re excited about the quesadilla! You’re spot on when it comes to re-heating caramelized onions. Simply put them in a skillet or small saucepan and heat them up on the stove. This is my preferred re-heating method over microwaving any day :) Have a great week!

    • Julia Mueller says

      Wahoo! So glad you’re into putting caramelized onions in your quesadillas as well! Beans would be excellent, thanks for a wonderful idea!

  3. says

    Let’s hear it for eating an avocado a day! I drizzle a little balsamic, salt, and pepper into mine and scoop it from the peel. YUM!

    I make quesadillas for my family once a week. Because I’m a vegan, and not a fan of vegan cheese (too processed), I make my own refried beans and use them for the “glue” to hold the ingredients together. They also create the creamy texture that cheese does. These look so good that I think I know what’s for dinner tonight.

    • Julia Mueller says

      That sounds delicious, Linda – both the way you eat your avocados and using refried beans in your quesadillas!! Hope you enjoy the quesadillas (minus the cheese, plus the beans) and let us know how your family likes them :D

    • Julia Mueller says

      Same here, Brittany – I tend to reserve quesadillas as an every-once-in-a-while thing, too. Let us know when you try it out!

    • Julia Mueller says

      Thanks so much for sharing the recipe, Christine! I love the creaminess of avocados and how versatile they are. I’m fully comfy eating an entire avo each and every day because of the healthy omegas. :D

        • Julia Mueller says

          Wow, that’s a really cool infographic!! I had no idea you could use avocado as sunscreen. The avos at my store have been rock solid lately, so you best believe I’ll be sticking them next to my bananas until they ripen, ha!

          I think folks are starting to embrace the fact that your body needs fat in order to absorb nutrients. I remember my friend’s parents being crazy over fat-free milk and now it seems like more households are embracing the fact that healthy fats should be embraced.

          You got me allllll fired up about healthy avocados and fat, haha! I’m totally fist pumping you right now ;)

          • says

            Hehe…Fist Pump!! Love it.

            I completely agree! People are starting to get off the low-fat bandwagon. More and more research has been coming out about ditching the old idea of low fat, and instead embracing the fat and limiting sugar.

            It helps that fat is also so tasty :)

    • Julia Mueller says

      Confession: I had some leftover caramelized onions when I made this recipe, so they totally went into a bowl…and then into my mouth. Caramelized onions for breakfast? Don’t mind if I do!

  4. says

    I can’t think of a more delicious-sounding quesadilla right now. Honestly, this sounds like such a tasty lunch (or dinner – or breakfast? Well, why not!) Great tip to freeze caramelized onions … I would never have thought of doing that.

    • Julia Mueller says

      Thanks, Helen! It really is an all-star meal! I wouldn’t be opposed to eating it for breakfast at all. I’d maybe even put a fried egg on top. mmmm!!

    • Julia Mueller says

      Glad you like it Meredith! It’s amazing how buttery and delicious caramelized onions and avocados are together. Seriously a flavor-blasted incredible combination!!

  5. says

    Oh my goodness – that looks *so* incredibly decadent and lovely! :D I’ve never made caramelized onions before, but I figure a splash of olive oil will do me good. Just need to make some cheese and this is 100% happening over the weekend!

    • Julia Mueller says

      Oh yes, you will become addicted to whipping up caramelized onions! They make everything taste soooo goooood! I’m impressed you make your own cheese! – a quesadilla with homemade cheese? Now that’s decadent!!

    • Julia Mueller says

      Wahooo! I’m so impressed that your daughter is adventurous enough to eat grown up quesadillas! My nieces and nephews are so boring with their food. They pretty much won’t touch anything that’s not the color of cheese, ha! :) Let us know how your daughter likes it!

  6. says

    My avocado allergy is making me really upset right now. But caramelized onions…they might just make up for it. What a quesadilla!

    • Julia Mueller says

      Oh man, Joanne!!! I didn’t know you were allergic to avocados. My avo-loving heart goes out to you. Caramelized onion and spinach quesadilla? Minus the avocado? I totally think that would work :)

  7. Zoe Kabe says

    This was absolutely delicious! I served this with the cilantro pesto and a little homemade salsa fresca. Looking forward to making this again. Thanks for the great recipe!

    • Julia Mueller says

      Awesome, Zoe! I’m so glad you tried and loved the quesadillas. I bet the cilantro pesto and salsa we amazing additions to the meal! All sorts of flavors! Thanks for the feedback, my dear.

  8. Katie C says

    As a college student living on my own (more importantly cooking for myself!) for the first time, I am always on the lookout for easy, healthy, and affordable meals. These were AMAZING. I halfed the recipe for myself and my roommate, and I was so happy with the results. I literally had never sliced an onion by myself up until tonight (not ashamed to say I looked up a how-to on youtube!). These were so easy and absolutely delicious. We added some chicken that we had left over as well. I am definitely adding this recipe to my list of recipes I love! Thanks!

  9. Bee says

    I made this for dinner last night and it was soooo good – so much so I am having it again for dinner tonight!

  10. Sandy says

    This looks and sound delicious. I definitely want to try this this weekend and it’s great that I can make and freeze the caramelised onions ahead of time.

  11. says

    This is amazing recipe, I made it one evening for a dinner!! I adapted a recipe a little bit to my needs, it was delicious!! Thanks for sharing!!! :)

  12. Sandy says

    Made this deliciousness for lunch today and it was as I said delicious ^_^. Made some mango salsa to go with it and all was good.

  13. Joie says

    I made this for dinner last night, and it was amazing! My husband and I both really enjoyed it. The flavors worked very well together. I will definitely make this again!!

    Thanks for the recipe.

  14. says

    I made this for a late Saturday breakfast today and it was so so good! I am guilty of not reading the recipe in full before starting, but serendipitously decided to make pico de gallo while my onions were caramelizing. The quesadilla itself was crazy tasty – something I would absolutely order out at a bistro. Having a bright, acidic pico on top brought it to another level. So so good and something I will make often. Thanks for posting!

  15. Amanda B. says

    Made this last night and it was AMAZING! And I forgot the salt! Even though we eat meat, we all felt that this dish was very filling, and that you don’t miss the meat at all. Thanks for creating this dish!

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