Caramelized Onion Puff Pastry Quiche

If you are looking for a decadent brunch recipe, you have to try this Caramelized Onion Puff Pastry Quiche!! 

Caramelized Onion Puff Pastry Quiche

I had some store-bought puff pastry in my freezer and thought it would be fun to make an easy quiche out of it. The only thing that took some time — caramelizing the onions. If you’ve never caramelized onions before, it does take a little bit of time, however, most of it is hands-off and the flavor is unparalleled, so WORTH IT. Why? Well, onions are naturally sweet and when cooking them low and slow, the natural sugars in the onions caramelize, leaving with an irresistible umami flavor. But if you want to save time the day of your brunch, I have notes below about caramelizing your onions ahead of time!

Caramelized Onion Puff Pastry Quiche

Caramelized Onion Puff Pastry Quiche

So yes, while caramelized onions are super easy to make, they do take time, but you’ll save time by not having to make a crust from scratch! And they bring so much flavor to this delicious veggie quiche. Making this Caramelized Onion Puff Pastry Quiche the perfect weekend brunch to treat you and your loved ones. 

Caramelized Onion Puff Pastry Quiche

Caramelized Onion Quiche
Serves: 6 People
5 from 2 votes
Prep Time1 hour
Cook Time40 minutes
Total Time1 hour 40 minutes


  • 1 sheet puff pastry thawed but cold if frozen, let thaw in the fridge for 24 hours
  • 4 tbsp olive oil, plus additional as needed (see below)
  • 1 large yellow onion, halved and thinly sliced
  • 1 tsp Kosher salt
  • 4 large eggs
  • 1 + 1/4 milk whole milk
  • 1 cup grated gruyere cheese
  • 1 tbsp dijon mustard
  • 2 cloves garlic minced
  • 2 cups sliced shiitake mushrooms, stem removed, sub baby bella mushrooms
  • ¼ tsp freshly ground black pepper
  • 2 cups swiss chard, stem removed and thinly sliced into ribbons (about 1 bunch)
  • 1 tsp fresh thyme leaves, finely chopped


Caramelize the Onions

  • Begin by caramelizing your onions. In a large skillet over medium heat, add 2 tbsp of the olive oil, onion and ½ tsp salt. Saute, stirring occasionally, until the onions are golden brown and caramelized, about 35-45 minutes. If your onions start to look slightly dry, add a drizzle of olive oil as needed. If they seem to be browning too quickly, adjust heat to medium-low.
  • After about 35 minutes of the onions cooking, start making the rest of your filling.

Make your Filling

  • In a large bowl, add the eggs, milk, cheese and Dijon mustard. Whisk to combine and set aside.
  • Once your onions are done cooking, remove from the heat and set aside to cool.
  • In the same pan used for the onions, add 2 tbsp olive oil, garlic, mushrooms, black pepper, and ½ tsp salt. Saute, stirring, until the mushrooms have softened, about 2-3 minutes.
  • Add the swiss chard and stir to combine, let cook for another 1-2 minutes until the swiss chard has slightly softened. Set aside to cool.

Assemble the Quiche

  • Preheat your oven to 400 degrees F and lightly grease your pie dish.
  • Roll the puff pastry sheet out to larger than the size of your pie plate. Press the pastry into the dish, folding over and gently stretching until it fits your dish, trimming if desired.
  • Once your veggies are cooled, add to your egg mixture and stir to combine. Next add the thyme and mix again then pour into your pan.
  • Pour the filling into the pastry. Bake, uncovered, until the filling is set and the crust is golden brown, 35-45 minutes. (if the top is starting to look overly browned, tent with a piece of foil.)
  • You want your eggs to be set; however, you want it to have a bit of a wobble to it as it comes out of the oven. It continues to cook and set as it rests and the wobble will ensure it has a silky, not rubbery, texture.
  • Remove from the oven and let cool for 5-10 minutes before slicing. Serve and enjoy!


For the Caramelized Onions: To save time the day of your brunch, I recommend caramelizing your onions the day before! Cook according to the recipe instructions, allow them to cool completely then store in an airtight container in the fridge until you are ready to make the filling the day of your brunch.


Food Photography and Styling by Modern Food Stories



  • Reply
    Laura gideon
    May 13, 2023 at 3:09 am

    I absolutely love the flavors in this quiche . I’m disappointed thought bc I’ve made it 3x and it comes out watery. How do I remedy this!?

  • Reply
    May 2, 2023 at 12:31 pm

    Hello! Could I use regular pie crust for this? I have an extra in the freezer 🙂

    • Reply
      May 4, 2023 at 4:38 pm

      Yes, definitely!

  • Reply
    April 7, 2023 at 10:55 am

    Could you use the plain unsweetened Nutpods creamer in place of the milk or should it be full fat coconut milk? If I use coconut milk, do I use the whole can or just the solids?

    • Reply
      April 11, 2023 at 6:09 pm

      Nutpods should work fine!! and yes– if you use the can, mix it up so that it’s all one consistency. I like to use this brand, it never separates and tastes great.

  • Reply
    April 4, 2023 at 6:36 pm

    Do you prebake the puff pastry? I see some recipes that do and some, like yours, that don’t?

    • Reply
      April 4, 2023 at 10:27 pm

      I didn’t and it turns out perfect.

  • Reply
    Anna Alpizar
    March 29, 2023 at 10:03 pm

    Could you make this without the cheese and with oat milk for a dairy free option? What would you sub instead?

    • Reply
      March 30, 2023 at 3:53 pm

      Yes– you could do it with a unsweetened full fat coconut milk. Just be aware that it is a lot of milk– so the taste will change.

  • Reply
    September 3, 2022 at 3:34 pm

    Pepper is missing from the directions.

    • Reply
      September 6, 2022 at 6:24 pm

      Great catch, just updated!

  • Reply
    Melissa C
    June 2, 2022 at 11:41 pm

    5 stars
    Fantastic quiche! I left out the Swiss Chard as my grocery store doesn’t carry it *gasp* but doubled the mushrooms and it came out so so delicious. I absolutely love the puff pastry crust. 5/5 stars!!

  • Reply
    May 9, 2022 at 2:22 pm

    I made this for Mother’s Day; I had never used puff pastry for a quiche before but we all LOVED it! I didn’t have Swiss chard or mushrooms, so instead I used the foundation elements of the recipe and subbed kale and bacon with the cartelized onion and gruyere–DELISH!!!!

  • Reply
    May 8, 2022 at 4:02 pm

    What cheese can you sub for the Gruyère?

    • Reply
      May 9, 2022 at 4:37 pm

      A shredded mozzarella would work too!

      • Reply
        March 29, 2023 at 10:49 pm

        1 + 1/4 milk whole milk? Is that cups?

        • Reply
          March 30, 2023 at 3:53 pm

          yes, sorry for that

  • Reply
    gail McClure
    May 7, 2022 at 9:44 pm

    Can I bake this ahead and just warm tomorrow before my family brunch?

    • Reply
      May 12, 2022 at 3:49 pm


  • Reply
    Vicki Ready
    May 6, 2022 at 11:13 pm

    5 stars
    Loved loved loved it! Can’t wait to serve it for a baby shower!

  • Reply
    Carol Bingham
    May 6, 2022 at 12:56 am

    Can you substitute some other veggies for the Swiss chard? Not a fan. The rest sounds wonderful! Spinach??

    • Reply
      May 9, 2022 at 5:18 pm

      spinach would work just fine!! The recipe is super versatile and you can really do whatever veggies you have on hand for the most part!

  • Reply
    May 6, 2022 at 12:54 am

    Could you make this without the puff pastry for gluten free?

    • Reply
      May 7, 2022 at 5:08 pm

      Some stores now carry GF quiche but you could also use these flavors to make a frittata instead.

  • Reply
    Andrea delman
    May 5, 2022 at 11:11 pm

    Is that a GF puff pastry, and if so, what brand?

    • Reply
      May 7, 2022 at 5:08 pm

      This is not but some stores do carry GF puff pastry! I have not used any yet.

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