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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 Quiche
5 from 3 votes

Caramelized Onion Puff Pastry Quiche

Prep: 1 hour
Cook: 40 minutes
Total: 1 hour 40 minutes
Servings: 6 People


  • 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.

Nutrition information is automatically calculated, so should only be used as an approximation.

Additional Info

Servings: 6 People


Food Photography and Styling by Modern Food Stories


Welcome! I’m Alex.

I’m a food lover sharing healthy, simple, delicious, recipes from my kitchen to yours. Here you’ll find lots of Whole30, lots of healthy, and a little indulgence here and there because…it’s all about balance y’all!

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Recipe Rating


  1. 5 stars
    Delicious. Made it for brunch on Sunday. I did add ground breakfast sausage (cooked first) to make it even more filling. With or without the sausage the flavors are incredible.

  2. 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!?

  3. 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?