Go Back
Brie and Caramelized Onion Tart Recipe
Ash Tyrrell

Brie and Caramelized Onion Tart Recipe

I still remember the first time I pulled this tart out of the oven and watched the brie bubble at the edges while the kitchen filled with that sweet, buttery onion smell. I made it for a small gathering, half expecting the sheet of puff pastry to fall apart on me, and instead it came out looking like something from a bakery window.
Print Recipe Pin Recipe
Prep Time 15 minutes
Cook Time 35 minutes
Servings: 6
Ingredients Method Notes

Ingredients
  

  • 1 sheet puff pastry thawed – this is your base, so let it thaw fully or it will crack when you unroll it
  • 2 large yellow onions thinly sliced – slice them evenly so they caramelize at the same rate
  • 1 tablespoon olive oil – helps the onions soften without sticking to the pan
  • 1 teaspoon sugar – speeds up caramelization and rounds out the onion's sharpness
  • 1/2 teaspoon salt – draws moisture out of the onions so they cook down faster
  • 6 ounces brie cheese sliced – go for a real wedge, not the pre-shredded kind, so it melts smoothly
  • 1 teaspoon fresh thyme leaves – fresh thyme gives a much brighter flavor than dried
  • 1 egg beaten – this is your egg wash for that golden, glossy crust
  • A pinch of black pepper – adds a little warmth against the sweetness of the onions

Method
 

  1. Heat the olive oil in a large skillet over medium heat, then add the sliced onions along with the sugar and salt. Let them cook low and slow, stirring every few minutes so nothing catches on the bottom of the pan. After about 15 to 20 minutes they should turn a deep golden brown and smell incredibly sweet. Pull them off the heat and let them cool slightly before handling.
  2. While the onions cool, preheat your oven to 400°F and line a baking sheet with parchment paper. Unroll the puff pastry onto the sheet and, if it is not already a neat rectangle, gently smooth it out with a rolling pin. Use a fork to prick the center a few times, leaving a small border untouched around the edges. This border is what puffs up into that pretty golden frame.
  3. Spread the cooled caramelized onions evenly over the pastry, staying inside the border you left. Lay the brie slices on top so they are spread out rather than piled in one spot, which helps the cheese melt evenly across the tart. Scatter the fresh thyme leaves over everything and finish with a small pinch of black pepper.
  4. Using your pastry brush, coat the exposed border of puff pastry with the beaten egg. This is what gives the crust that shiny, bakery-style finish once it comes out of the oven. Try not to let the egg wash drip down the sides, since it can glue the pastry to the parchment paper.
  5. Slide the tart into the preheated oven and bake for 20 to 25 minutes, until the pastry is puffed and deeply golden and the brie has melted into soft, gooey pools. Every oven runs a little differently, so start checking around the 18-minute mark if yours tends to bake hot.
  6. Let the tart rest on the baking sheet for about 5 minutes before transferring it to a cutting board. This short rest lets the cheese set just enough that it will not run everywhere when you slice it. Cut it into squares or wedges and serve while it is still warm.

Notes

  • I always slice my onions the same thickness so they cook evenly instead of some burning while others stay raw.
  • I let the caramelized onions cool for a few minutes before adding them to the pastry, otherwise the butter in the dough starts to soften too early.
  • I chill the assembled tart in the fridge for 10 minutes before baking if my kitchen is warm, since cold pastry puffs up better.
  • I use a light hand with the egg wash because too much pooling on the parchment makes the edges soggy instead of crisp.
  • I always bake on the middle rack, since the bottom rack browns my crust too fast before the center sets.