Caramelized Onion Rustic Tart (Print)

Flaky pastry topped with golden caramelized onions and creamy cheese for a savory delight.

# Components:

→ Pastry

01 - 1 sheet frozen puff pastry, thawed (approximately 9 oz)

→ Onions

02 - 3 large yellow onions, thinly sliced
03 - 2 tablespoons unsalted butter
04 - 1 tablespoon olive oil
05 - 1 teaspoon granulated sugar
06 - 1/2 teaspoon salt
07 - 1/4 teaspoon freshly ground black pepper

→ Filling & Topping

08 - 1/2 cup crème fraîche or sour cream (4 fl oz)
09 - 1 teaspoon Dijon mustard
10 - 1/2 cup grated Gruyère cheese (2 oz)
11 - 1 teaspoon fresh thyme leaves or 1/2 teaspoon dried thyme
12 - Optional: 1 tablespoon chopped fresh chives for garnish

# Directions:

01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large skillet over medium heat, melt the butter with olive oil. Add sliced onions, sugar, salt, and black pepper. Cook, stirring frequently, until onions turn deep golden and caramelize, about 25 to 30 minutes.
03 - On a lightly floured surface, roll the puff pastry into a 12-inch square or circle. Transfer it to the prepared baking sheet.
04 - Combine crème fraîche and Dijon mustard in a small bowl. Spread evenly over the pastry, leaving a 1-inch border around the edges.
05 - Sprinkle half of the grated Gruyère cheese over the crème mixture. Distribute the caramelized onions atop the cheese, then scatter thyme leaves. Finish with the remaining Gruyère cheese.
06 - Carefully fold the edges of the pastry over the filling to create a rustic border.
07 - Bake for 20 to 25 minutes until the pastry is golden and crisp. Allow to cool slightly before slicing.
08 - Optionally garnish with fresh chopped chives. Serve warm or at room temperature.

# Expert Advice:

01 -
  • It looks like you spent all day in the kitchen, but the actual work is just slicing onions and waiting for magic to happen.
  • The contrast between buttery pastry and sweet, jammy onions is the kind of flavor that makes people ask for the recipe before theyve finished their slice.
02 -
  • If your onions start to stick or darken too fast, lower the heat and add a splash of water to the pan, then keep stirring.
  • Rolling the pastry too thin will make it soggy under the onions, leave it about an eighth of an inch thick and it will stay crisp.
03 -
  • Slice your onions as thinly and evenly as possible so they caramelize at the same rate and you dont end up with some burnt and some raw.
  • If the pastry puffs up too much in the center while baking, gently press it down with a spatula halfway through and it will settle.
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