Italian Caramelized Onion and Gorgonzola Tart

About This Recipe

This tart draws on the classic Italian pairing of sweet caramelized onions and pungent blue cheese, a combination found in regional dishes across northern Italy where Gorgonzola is produced. Thinly sliced onions are cooked low and slow until deeply golden and jammy, spread over puff pastry, and dotted with crumbled Gorgonzola before baking until the pastry puffs and turns deep golden. The technique that matters most is genuinely caramelizing the onions -- not just softening them, but cooking them 30-40 minutes over low heat, stirring occasionally, until they turn a deep amber and taste sweet rather than sharp. Rushed onions at high heat will brown unevenly and taste bitter rather than achieving that sweet, jammy quality that makes the tart work. Baked until the pastry is crisp and golden and the cheese has melted into pockets throughout the onions, this tart is simple enough for a weeknight but elegant enough for guests, best served slightly warm so the Gorgonzola stays soft and the pastry stays crisp.

Ingredients

Serves 4

• 4 largeonions(thinly sliced)
• 3 tbspbutter
• 1 tbspolive oil
• 1 tspsalt
• 1 tbspbalsamic vinegar
• 1 sheetpuff pastry(thawed)
• 150 gGorgonzola(crumbled)
• 1egg(beaten, for egg wash)
• 1 tbspfresh thyme leaves
• 2 tbspwalnuts(chopped, optional)

Instructions

1. 1

   Caramelize the onions

   Melt butter with olive oil in a wide skillet over medium-low heat. Add onions and salt, cook, stirring occasionally, 30-40 minutes until deeply golden and jammy.

2. 2

   Deglaze

   Stir in balsamic vinegar during the last 2 minutes of cooking, scraping up any browned bits. Remove from heat and cool slightly.

3. 3

   Prepare the pastry

   Preheat oven to 200C/400F. Roll out puff pastry on a lined baking sheet and score a border about 2cm from the edge without cutting all the way through.

4. 4

   Assemble

   Spread caramelized onions within the scored border. Dot with crumbled Gorgonzola and scatter thyme leaves.

5. 5

   Egg wash and bake

   Brush the pastry border with egg wash. Bake 25-30 minutes until the pastry is puffed and deep golden.

6. 6

   Serve

   Scatter with walnuts if using, slice, and serve warm.

Variations

• •

  Use goat cheese instead of Gorgonzola for a milder, tangier flavor.

• •

  Add crispy pancetta or prosciutto for a heartier, non-vegetarian version.

• •

  Make individual smaller tarts instead of one large one for easier portioning at a dinner party.

Storage

Refrigerate covered up to 3 days. Reheat in a 180C/350F oven for 8-10 minutes to recrisp the pastry; avoid microwaving as it makes the crust soggy.

Frequently Asked Questions