I made caramelized onion and gorgonzola puff pastry tarts for John’s housewarming party. They were definitely one of the party favourites. They were also easy to prepare in advance. I cut them into small squares for finger food, but this tart would make a great first course, too. If you have the time and patience, you could turn these into round hors d’oeuvres instead. These would be cute and elegant for any event. Simply use a small, round cookie cutter to cut out rounds of the rolled out dough, follow the recipe as written, and place the filling onto each round of dough before baking.
Caramelized Onion Tart with Gorgonzola Recipe
adapted from Nick Malgieri’s The Modern Baker; This recipe makes one large rectangular tart (approximately 12 inches x 15 inches) that can be cut into, up to, 36 pieces, depending on the desired size. Alternatively, for a cuter and more elegant variation, you could make bite sized, round hors d’oeuvres instead. Simply use a small, round cookie cutter to cut out rounds of the rolled out dough, follow the recipe as written, and place the filling onto each round of dough before baking. This recipe doubles well.
1/4 batch of chilled homemade puff pastry (see recipe here) or 1 box (397 gram) store-bought frozen puff pastry, defrosted in the refrigerator
all purpose flour
approximately 2 pounds or 4 large onions, finely chopped
3 tablespoons olive oil or vegetable oil
2 tablespoons balsamic vinegar
1 tablespoon brown sugar
pinch coarse Kosher sea salt
freshly ground black pepper
1 scant cup of gorgonzola or other blue cheese, crumbled (Note: If you are worried that people might not like blue cheese, try cambozola or borgonzola for a milder blue flavour. I’ve used cambozola before with great success.)
1 to 2 tablespoons chopped fresh tarragon
Pour the olive oil into a wide saute pan. Add the onions and place the pan over medium heat, covered. Once the onions start to sizzle, reduce the heat and continue to cook until the onions become soft and translucent, about 15 minutes. Then remove the lid, increase the heat slightly, and add the brown sugar, vinegar, pinch of salt, and a large pinch of pepper. Cook the onions, uncovered, stirring occasionally, until the onions are caramelized and all of the liquid has evaporated, about 20 to 25 more minutes. Transfer the onions to a wide mouthed bowl or plate and allow them to cool completely at room temperature. The onions can then be refrigerated for 1 or 2 days, if you are making the onion topping in advance. Meanwhile, prepare the dough.
On a well floured work surface, use a rolling pin to press the dough into a square shape. Then gently roll the dough into a rectangle, approximately 12 inches x 15 inches. The dough will be thin. It is important to work quickly so that the dough remains cold. If it becomes too soft, chill it through in the refrigerator before rolling again. Straighten the edges and make the corners even. Then slide the dough onto a parchment paper or silpat mat lined baking sheet, cover it using syran wrap, and chill it through in the refrigerator. Note that the dough can be rolled out up to 1 day in advance.
Once the dough is chilled through, use the tines of a fork to pierce holes, 1 inch apart, throughout the dough. Leave a one inch border around the tart if desired. Spread the onion mixture evenly across the dough. Then scatter the crumbled gorgonzola cheese over the onions. Sprinkle over the taragon. Cover the tart with syran wrap and refrigerate it until 1 hour prior to when you want to serve it. Note that this tart can be assembled in advance, several hours prior to baking.
One hour before you want to serve the tart, set a rack in the middle of the oven and preheat it to 400 degrees F (200 degrees C). Bake the tart in the preheated oven until the pastry is baked through, lightly browned, and crispy, and the cheese is melted, about 15 minutes. Transfer the baking sheet to a wire rack and cool for 5 minutes. Then cut the tart into squares of your desired size. Serve immediately. If you are serving this tart as a first course to a meal, you may want to plate this with a small and simple, lightly dressed, salad.