Caramelized Onion Puff Pastry Quiche As seen on The Defined Dish Bookmark recipe Print recipe Download recipe Share Total Time 1 hour and 40 minutes Prep Time 1 hour Cook Time 40 minutes Rating 5 out of 5 stars (4) Ingredients 6 servings 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 salt4 large eggs1 + 1/4 cup whole milk1 cup grated gruyere cheese1 tbsp dijon mustard2 cloves garlic (minced)2 cups sliced shiitake mushrooms, (stem removed, sub baby bella mushrooms)¼ tsp freshly ground black pepper2 cups swiss chard, (stem removed and thinly sliced into ribbons (about 1 bunch)1 tsp fresh thyme leaves, (finely chopped) Calories BakingVegetarianDinnerDairyEggsIntermediateVegetablesFrenchLunchFall ... How would you rate this recipe? 1 stars 2 stars 3 stars 4 stars 5 stars Preparation Inline ingredients (beta) Cook mode Click to complete Step 1 Caramelize the Onions Step 2 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. Step 3 After about 35 minutes of the onions cooking, start making the rest of your filling. Step 4 Make your Filling Step 5 In a large bowl, add the eggs, milk, cheese and Dijon mustard. Whisk to combine and set aside. Step 6 Once your onions are done cooking, remove from the heat and set aside to cool. Step 7 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. Step 8 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. Step 9 Assemble the Quiche Step 10 Preheat your oven to 400℉ and lightly grease your pie dish. Step 11 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. Step 12 Once your veggies are cooled, add to your egg mixture and stir to combine. Next add the thyme and mix again. Step 13 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. Step 14 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. Step 15 Remove from the oven and let cool for 5-10 minutes before slicing. Serve and enjoy!