Caramelized Onion Tart with Gorgonzola

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Preparation info

  • Makes


    10 × 15 inch 25 × 38 cm ) tart, enough for about 3 dozen 2 inch 5 cm ) hors d’oeuvres
    • Difficulty


Appears in

The Modern Baker

The Modern Baker

By Nick Malgieri

Published 2008

  • About

This delicious hors d’oeuvre or first course was devised by my friend Bonnie Stern, Canada’s foremost authority on food and cooking. I’ve taught many times at Bonnie’s cooking school in Toronto, though I first tasted this tart in New York at an event promoting Canada. It’s a little like a focaccia, but here puff pastry substitutes for the yeast dough.


  • ¼ batch Instant Puff Pastry, or about 12 ounces (350 grams) prepared all-butter puff pastry
  • 4 large onions, about 2 pounds (900 grams), chopped
  • 3 tablespoons olive oil
  • 1 tablespoon light brown sugar
  • 2 tablespoons balsamic vinegar
  • ½ teaspoon salt
  • ½ teaspoon freshly ground black pepper
  • 8 ounces (350 grams) Gorgonzola or other blue cheese, crumbled
  • 3 tablespoons chopped fresh tarragon
  • 1 jelly-roll pan lined with parchment or foil


  1. Press the Instant Puff Pastry dough into a rough square, then roll it into a 12 × 15- inch (30 × 38-cm) rectangle. Roll gently, and if the dough resists, let it rest for 5 minutes, then roll again. If at any point the dough becomes too soft to handle, slide a cookie sheet under it and refrigerate for 10 to 15 minutes.
  2. Once the dough is rolled to the correct size, straighten the edges and make the corners even and slide it into the prepared pan. Chill the dough while preparing the topping.
  3. For the topping, combine the onions and oil in a wide sauté pan with a lid. Cook, covered, over medium heat until the onions start to sizzle. Lower the heat and cook until the onions become tender and translucent, about 15 minutes. Uncover the onions, increase the heat slightly, and add the sugar, vinegar, salt, and pepper. Continue to cook the onions, stirring occasionally, until they are richly caramelized, 20 to 25 minutes longer.
  4. Scrape the onions into a shallow bowl and refrigerate briefly to cool.
  5. Remove the dough from the refrigerator and pierce it with the tines of a fork at 1- inch (-cm) intervals. Spread the cooled onion mixture evenly over the dough. Scatter the cheese on top, then sprinkle with the tarragon. Cover with plastic wrap and refrigerate it until about 1 hour before you want to serve it. You may assemble the tart up to 24 hours before baking it.
  6. About 1 hour before you want to serve the tart, set a rack in the middle of the oven and preheat to 400°F (200°C).
  7. Bake the tart until the pastry is baked and crisp and the cheese is melted, about 20 minutes.
  8. Cool in the pan on a rack for 5 minutes, then cut into portions. Serve immediately.


As an hors d’oeuvre, serve slices along with some salted almonds and a few stalks of fresh fennel. As a first course, garnish the plate with a small frisée salad simply dressed with a little oil and lemon juice whisked together with a pinch of salt.


You may roll out the dough and cook the onions the day before, but assemble and bake the tart on the same day. There won’t be any leftovers.