Caramelized Onion Puff Pastry Quiche

If you are looking for a decadent brunch recipe, you have to try this 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!

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

Serves: 6 People

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5 from 2 votes

Prep Time1 hour hr

Cook Time40 minutes mins

Total Time1 hour hr 40 minutes mins

Ingredients

• 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

Instructions

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!

Notes

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.