Wild Mushroom, Potato and Onion Puff Pastry Tart

Wild Mushroom, Potato and Onion Puff Pastry Tart

Cook time: 30


  • 1/4 cup / extra-virgin olive oil
  • 1 lbs / russet potatoes, peeled and sliced 1/4 inch thick (mandolin is quickest)
  • 2 tsps / kosher salt
  • 1 small / onion, thinly sliced
  • 1 lbs / mixed mushrooms (white, cremini, shitake, oyster, etc.) thinly sliced.
  • 1 Tblsp / fresh thyme leaves, chopped
  • 1 cup / heavy cream
  • 2 sheets / frozen puff pastry, thawed according to box directions
  • All purpose flour, for rolling
  • 1 cup / grated Italian Fontina (Whole Foods, Moriano's, Oliver's)
  • 1/2 cup / grated Grana Padano (similar to Parmesan cheese but not made to the same strict standards and usually a bit cheaper. Buy a piece and grate yourself )


  1. Preheat oven to 400 degrees. Heat the oil in your largest, large nonstick skillet over medium-high heat. When the oil is hot, add the potatoes, and cook, tossing frequently, until they are crisp and golden (but they don’t need to be entirely cooked through at this point), about 7 minutes. Drain on paper towels and season with 1 teaspoon of the salt.
  2. Wipe the skillet clean. Over medium heat, melt the butter. When it is melted, add the onion and cook until it begins to wilt, about 3 to 4 minutes. Add the mushrooms, and season with the thyme and remaining salt. Cover, and cook until the mushrooms have given up their juices, about 2 to 3 minutes. Uncover, and increase the heat to reduce the liquid away, about 2 to 3 minutes more. Add the cream, and boil until reduced by half, about 2 minutes. Pour the mixture into a bowl, add the potatoes, and toss to combine. Let cool. (Spread on baking sheet for faster cooling).
  3. Line a large, flat sheet pan with parchment paper, helps to move finished tart. Lightly flour a clean work surface and unfold the puff pastry and gently flour both side, then line the two pieces up on the parchment with a slight overlap. Roll to fuse the two pastry sheets together and all the way to the edges of the cookie sheet.
  4. In a medium bowl, toss together the Fontina and Grana Padano. Spread the filling over the puff pastry, leaving a 1-to-2-inch border. Fold the border edges of the pastry up and over the edges of the mushrooms to form a crust. Sprinkle the exposed part of the filling with the cheese mixture and just a few finger fulls on the crust.
  5. Bake until pastry is crisp and golden and cheese is brown and bubbly, about 30 minutes. (Time is perfect). Using the ends of the parchment paper, slide off the cookie sheet and onto a cooling rack, I used the same size baking sheet bottom up. Cool at least 15 minutes before cutting into squares to serve.