Perfect for meal prep or a quick weekday lunch, this Chicken Zucchini Sandwich with Caramelized Onions is an excellent way to use up that leftover rotisserie chicken sitting in your fridge. The zucchini adds a bright, slightly acidic bite that cuts through the richness of the cream cheese and onions.
Thinly sliced rotisserie chicken, tangy marinated zucchini (hello, leftovers from my za’atar zucchini walnut salad), a generous smear of cream cheese, and sweet caramelized onions all stacked between two slices of toasted bread.
This sandwich comes together in about 10 minutes if you’ve already got the components prepped, making it perfect for meal prep or a quick weekday lunch. It all starts with a bright, zesty zucchini salad, and every other element can be made in advance, then stored separately. All you have to do is put them together and assemble the sandwich.
Chicken Zucchini Sandwich with Cream Cheese Caramelized Onions
This sandwich is all about strong components coming together for a super flavorful dish. Full of shortcuts, it can be easily adapted and customized to what you have on hand. With that said, every element here plays an important role, balancing each other out and building flavor:
Rotisserie chicken is the ultimate shortcut. I love keeping one in the fridge for convenience, and moments like this, when I need a quick, protein-rich meal. All you have to do is thinly slice it.
Marinated zucchini from my zucchini salad brings acidity and texture. It’s a great way to use the leftovers, since the zucchini gets a chance to marinade in the tangy dressing, providing crunch and a nice punch of flavor. You can also just use zucchini slices seasoned with lemon, salt, and pepper instead.
Cream cheese adds a creamy, tangy base that holds everything together. It pairs beautifully with the zucchini and caramelized onions.
Caramelized onions add a deep, slightly sweet flavor that balances the brightness of the zucchini and complements the creaminess of the cream cheese. Make a batch ahead and store in the fridge – they keep in the fridge for about a week.
It All Starts with Zucchini
This sandwich came to be because I had leftover zucchini salad. A bright, zesty salad that was all about layering simple ingredients while building depth of flavor. Thinly sliced zucchini is tossed in a warm, infused olive oil with garlic, lemon zest, and za’atar, so it immediately starts absorbing those flavors.
The lemon juice keeps everything bright, while the zucchini stays tender and delicate with just a bit of bite.
Toasted walnuts add crunch and richness, parmesan brings a salty, savory finish, and lots of fresh mint add a herby touch. This salad is a balance of bright, nutty, herby, and savory.
If you have leftovers, you’ll notice that as the salad sits, the zucchini keeps soaking up even more of the infused oil, lemon, and za’atar, becoming more flavorful.
That’s exactly why it works so well in this sandwich. Not only do you get the freshness of the zucchini, but you also get the crunch of the walnuts, the saltiness of the parmesan, and the brightness of the dressing right into your sandwich.
How to Caramelize Onions
Caramelizing onions takes patience, but very little active time. Sliced onions are slowly cooked over moderate heat until their natural sugars break down and turn deeply golden, becoming naturally soft, and sweet in the process.
You can add them to everything from sandwiches to soups, so it’s not a bad idea keeping a small batch in the fridge!
Start by thinly slicing your onions so they cook evenly. Heat a wide pan over medium to medium-low heat and add a bit of oil or butter. Add the onions with a pinch of salt (the salt helps draw out moisture), then let them cook slowly, stirring every so often, so they don’t stick to the bottom of the pan.
Unfortunately, you can’t really rush the process, it’s all about time. At first, the onions will soften and release water. Then they’ll begin to turn lightly golden, and eventually deepen into a rich brown. This process usually takes 25-40 minutes, depending on the heat and quantity.
I like adding a splash of balsamic vinegar halfway through the cooking, but that’s optional. You’ll probably have to deglaze the pan every once in a while, because the onions do insist on sticking to the pan; for that I like to use chicken stock or just water. A splash is enough to loosen them.
Tips for best results:
- Don’t rush it: High heat will burn the onions instead of caramelizing them. Keep it moderate and steady.
- Use a wide pan: Overcrowding traps steam and slows browning.
- Stir, but not constantly: Let them sit long enough to develop color, then stir to prevent sticking.
- Deglaze if needed: If bits start sticking to the pan, add a splash of water to or stock loosen them.
- Finish when deeply golden: You’re looking for a jammy texture and rich, sweet flavor.
Tips for the Best Chicken Zucchini Sandwich
- Warm the chicken! Room temperature chicken is fine, but 20 seconds in the microwave makes the sandwich much better, so I highly recommend doing it.
- Make caramelized onions in bulk. They take 30-40 minutes to make properly, so do a batch and refrigerate. They’re great on eggs, soups, tarts – basically everything.
- Try different breads. I like a softer, rich bread like brioche, but sourdough, ciabatta and focaccia all work well.
Storage and Meal Prep
Prepped components (chicken, zucchini, onions) keep separately in the fridge for 4-5 days. Assemble the sandwich fresh when ready to eat for best texture.
Packed lunches: If packing for later, keep the bread separate from the fillings and assemble just before eating. Alternatively, use a sturdier bread like ciabatta that won’t get soggy as quickly.
Variations
- Add pesto. Swap the cream cheese for basil pesto for a bright, herby version.
- Make it a melt. Add a slice of provolone or mozzarella and press in a panini press until the cheese melts.
- Swap the protein. Turkey, leftover grilled chicken, or even smoked salmon work well with this flavor profile.
You Might Also Like…
Chicken Salad Sandwich: A fresh, balanced take on a classic; creamy, crisp, slightly sweet. Perfect for an easy, satisfying lunch or snack.
Caramelized Onion Zucchini Galette: Jammy caramelized onions and zucchini layered into a flaky pistachio crust. Simple, savory, and deeply flavorful.
Cantaloupe Salad with Radishes, Cucumbers & Parmesan: Sweet, crisp, and refreshing with a salty edge; the kind of salad that hits every note.
Caramelized Onion and Pear Tart: Sweet pears and deeply caramelized onions come together in a rich, savory tart that feels just a little bit elevated.
Chicken Zucchini Sandwich with Caramelized Onions
Ingredients
- Bread of choice (brioche, challah, sourdough, or focaccia)
- Rotisserie chicken, thinly sliced
- Cream cheese
- Caramelized onions (see above)
Leftover zucchini salad
Instructions
- Toast the bread until golden.
- Warm the sliced rotisserie chicken in a skillet over medium heat, or in the microwave until just heated through.
- Spread cream cheese over the toasted bread. Add a generous spoonful of zucchini salad.
- Layer the warm chicken over and top with caramelized onions.
- Close the sandwich and serve immediately.
