Caramelized Fennel and Onions

Sliced onions and fennel, slowly cooked until lightly browned, tossed with Parmesan, lemon, and parsley.

  • Prep time: 10 minutes
  • Cook time: 1 hour
  • Yield: Serves 4


  • 2 large onions, halved then sliced lengthwise (root to tip) in 1/4-inch thick slices
  • 2 large fennel bulbs, sliced into 1/4-inch thick slices
  • 1/4 cup olive oil
  • 1 Tbsp butter
  • Salt
  • 1/4 cup grated Parmesan
  • 2 Tbsp chopped fresh parsley
  • 1 teaspoon lemon zest
  • 2 teaspoons lemon juice


1 Cook fennel and onions in olive oil and butter: Heat olive oil and butter in a large, uncovered, wide pan on medium high heat. Add the sliced fennel and onions and stir to coat. Stir occasionally.

After about 10 minutes, sprinkle the onions and fennel with salt. Lower the temperature to medium.

You want to strike a balance between allowing the pan to get hot enough so that some caramelization (when the natural sugars in the onion and fennel start to brown) and keeping the pot from getting so hot that the onions and fennel dry out.

If it becomes an issue, you can add a couple tablespoons of water to the pan to help the onions and fennel to keep from drying out too much.

2 Scrape up browned bits: Stir occasionally, scraping up any browned bits from the bottom of the pan. Note that the browned bits are the tastiest parts.

Cook for another 30 minutes to an hour, depending on how much of a hurry you're in, and how caramelized you want your mixture to be. The longer you cook, the more caramelized and browned.

Taste test along the way to see if the cooking has been sufficient for your taste.

By the way, the onions and fennel will have plenty of flavor without having to be completely cooked down and browned all over.

3 Toss with Parmesan, parsley, lemon: When ready to serve, remove from heat and toss in the freshly grated Parmesan cheese, the chopped parsley, lemon zest and lemon juice. Taste and add more lemon juice if necessary.

Serve alone as a side to chicken or seafood, or on crackers or thinly sliced toasted baguette for a crostini. You can also use it as a filling for a rustic tart.

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  • Bev

    Delicious, no doubt about it!!!

  • Melinda

    Love it, made it to add to gourmet grilled cheese.


  • ramona dupre'

    I love liver with onions. How do you cook the onions?

  • kwilkinson

    This recipe was wonderful. It was easy to make and it even is a great leftover! Don’t panic if the onions and fennel overflow the pan at first, just keep stirring, it will cook down. This recipe will be made again.


  • Amanda Delp

    What kind of pan do you use to cook this? I originally thought of a cast-iron skillet, but since you specify “pan”, I’m unsure. It sounds wonderful and very simple to make – my favorite kind of recipe. Thanks!

    Hello Amanda, I used a large, hard anodized aluminum pan to cook this, which is naturally stick-free, but you could easily use a large cast iron skillet. ~Elise

  • MVI

    I made this but did a vegan version as I can not eat dairy and it was absolutely fantastic. I just used Earth Balance in place of the butter and about a tablespoon of nutritional yeast in place of the cheese. The longer it cooks the more sweet it becomes. It was so good that I ate it all by itself but next time will make more and use it on pizza or with a veggie burger. Excellent and simple to make.

  • Linda Buckner

    Made this last night as a side for fresh, wild caught Copper River Salmon filet. It was a winner! I gave it the full hour plus a little more as we waited for the green beans. There was a tiny bit left over that will become crostini tonight!

  • Morena

    Fennel and onion… what a delicious combination, full of flavor and so versatile. I am inspired to have this veggies with Peruvian asado for dinner. I am sure it will be amazing. Will let you know…

  • Arcey

    I had a delicious caramelized fennel soup at the De Young Museum Cafe in SF last year, that I’ve been meaning to duplicate. I’ve bought fennel at least 2 or 3 times since then, intending to make the soup, but got lazy and ended up just using it in salads or tossing the (by then) slimy fennel.

    I hope this recipe has inspired me once again to make the soup. I would have used lots of caramelized onions as well. I think this recipe above can easily be used as the base of a soup. Try it!

    What a great idea, thanks! ~Elise

  • Jane

    I do this all the time. It’s heavenly mixed with a little bit of cream or butter and fettuccine, served with seared scallops.

  • Brandon @ Kitchen Konfidence

    Funny! I just made a caramelized fennel and onion (shallot) pizza last night. I simply caramelized in olive oil and seasoned with salt, pepper and fresh thyme. So amazingly tasty. I love fennel :)

  • CJ McD

    Put that on your pizza…..

  • Edith

    You caught me! For a while, I braised fennel in quarters, just as another of your recipes outlines. Then, I got lazy and starting slicing the fennel (like an onion) and proceeding with what I’d call more ‘stir fry’ than ‘braise.’ I still use salt and sugar, but the loose strips cook faster than braising the fennel in quarters. Faster cooking means faster for me to eat it right out of the pan!

  • Cassie

    Looks so delicious… I am a huge onion fan, most definitely. My farmer’s market hasn’t had any fennel yet though. I agree with the comment above that it would be a great burger topping.

  • laura @ glutton for nourishment

    i *adore* fennel, and i *adore* caramelized onions (or caramelized anything for that matter). this might be a little unorthodox, but i’m thinking this would be great as a burger topping at our memorial day bbq…

  • Elisha

    I LOVE fennel- raw or cooked- but my husband hates it. Every few months I try making it a different way but it doesn’t seem to help – it’s the anise flavor that gets him. Sigh. It’s the same way with mint, and with the summer upon us I dream about fresh mint in drinks, salads and dessert.

    Hi Elisha, my father hates fennel too. But when I served him some of this, he went back for seconds. He loved it. ~Elise

  • Sharkey

    Looks great. I have friends who make a great caramelized onion quiche out of Julia Child’s cookbook. Would this combination of fennel and onion work in a quiche?

    It would work great in a quiche! ~Elise

  • Vikker

    I am so making this to go with the Roast chicken we are having tonight.