Crostata With Mushrooms and Onions

PREPARATION

Preheat oven to 400 degrees. Heat the oil in a 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 1⁄2 teaspoon of the salt. 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.

Line a flat sheet pan with parchment. Unroll the puff pastry, lightly flour both sides, and line the two pieces up side by side on the parchment. Roll to fuse the two pastry sheets together, all the way to edges of the cookie sheet. In a medium bowl, toss together the Provolone and Pecorino. Spread the filling over the puff pastry, leaving a 1-to-2-inch border. Fold the edges of the pastry over to form a crust. Sprinkle the exposed part of the filling with the cheese mixture. Bake until pastry is crisp and golden and cheese is brown and bubbly, about 30 minutes.

Slide off of the cookie sheet and onto a cooling rack. Cool at least 15 minutes before cutting into squares to serve.