Caramelized Onion and Phyllo Tart

updated Jan 21, 2020
Caramelized Onion and Phyllo Tart
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Credit: Brie Passano

Caramelized onions are the backbone of many dishes, but it’s time to give these humble alliums a turn in the spotlight. Sweet and deeply flavored, a tart covered with caramelized onions needs little embellishment and is a great way to use up the big bag of onions you picked up at the grocery store or farm stand.

Credit: Brie Passano

Don’t Fear Phyllo

The bed of this tart is made of flaky layers of phyllo dough flavored with an herb-infused olive oil. Phyllo dough may seem like a hard ingredient to work with, but the thing to remember is that you never use just one phyllo sheet at a time. They’re always stacked together to create flaky layers, so if it rips, don’t panic — just patch the holes together. It’ll all come together just fine.

Slow-Cook Your Onions

This tart needs a large amount of caramelized onions, which means that you need to start with an even larger amount of raw onions since they cook down so much. Caramelizing that many onions takes a lot of stovetop cooking time, so turn to your slow cooker instead. Make a big batch in your slow cooker and freeze the caramelized onions so that you can make this tart whenever the craving hits.

Another Key Ingredient for This Caramelized Onion Tart

This tart has creamy Boursin cheese and fresh herbs, but it needs something bright and acidic to cut through all the richness. A handful of peppery arugula tossed with lemon juice adds freshness and a bright zip of color to this tart. Serve it as an elegant first course or appetizer.

Farm Stand Freestyle

There’s lot to love about a farm stand: no lines, great prices, and usually some of best homestyle baked goods in town. We like to load up on produce when we head to a farm stand and use that bounty in big-batch recipes that call for a sizable amount of fruits or veggies. Even if your bounty is coming from the garden or an abundant CSA, any of these recipes designed to use up a few pounds of fruits and veggies are the ones to try.

Caramelized Onion and Phyllo Tart

Serves 12 as an appetizer

Nutritional Info


  • 2 cups

    caramelized onions

  • 2 tablespoons

    plus 1 teaspoon finely chopped parsley leaves, divided

  • 1 1/2 teaspoons

    finely chopped fresh thyme leaves, divided

  • 1/3 cup

    olive oil

  • 10

    (14x18-inch) phyllo sheets (about 8 ounces), defrosted if frozen

  • Kosher salt

  • Freshly ground black pepper

  • 1

    (5.2-ounce) box garlic and herb Boursin cheese

  • 2 cups


  • 1 teaspoon

    freshly squeezed lemon juice


  1. Arrange a rack in the middle of the oven and heat to 400°F. Line a standard 18x13-inch rimmed baking sheet with parchment paper; set aside.

  2. Place the onions, 2 tablespoons of the parsley, and 1 teaspoon of the thyme in a medium bowl and mix to combine; set aside. Add the remaining 1 teaspoon of parsley and 1/2 teaspoon of thyme to the olive oil and stir to combine; set aside.

  3. Lay 1 sheet of phyllo on the prepared baking sheet. Keep the remaining phyllo covered with plastic wrap, wax paper, or a damp kitchen towel. Brush the phyllo with a thin layer of the herb oil. Repeat with the layers of phyllo, brushing each layer with oil, until all the phyllo is used up, making sure to brush the top layer of phyllo with the oil.

  4. Season the surface of the phyllo with salt and pepper. Carefully roll about 3/4-inch of each side in on itself toward the center to form the outer rim of the flatbread. Spread the onions evenly over the phyllo. Crumble the Boursin evenly over the onions.

  5. Bake until the edges are golden-brown and crisp, about 30 minutes. Transfer the tart to a cutting board.

  6. Place the arugula and lemon juice in a medium bowl, season with salt and pepper, and toss gently with your hands to combine. Sprinkle the tart evenly with the dressed arugula, cut into 12 pieces, and serve warm or at room temperature.

Recipe Notes

Phyllo: Defrost frozen phyllo dough overnight in the refrigerator.

Room temperature: This tart can also be served at room temperature. Top with the dressed arugula right before serving.

Storage: Leftovers can be stored in an airtight container for up to 5 days. Reheated in a 300°F oven until warmed through, 10 to 12 minutes.