This recipe is inspired by one in a favorite cookbook of mine, Cucina & Famiglia by Joan Tucci and Giovanni Scappini. Giovanni recommends baking this in 10-inch Springform pan, but you can also roll out the dough to fit a 9 x 15-inch baking sheet with a 1" rim; cut the baked tart into small cubes and serve it as an appetizer hot or at room temperature.
I particularly like the flavor of this crust for a savory pie. It is a sticky dough, so the refrigeration step is important for successfully rolling out the crust. Otherwise, it is a fairly simple and elegant meal, especially if the greens have been prepared the day before.
For the Pastry:
2 1/2 cups all-purpose flour
2 tsp Kosher salt
Freshly ground pepper
15 TBS cold butter, cut into small pieces
1 large egg yolk
1/2 cup water
1/4 cup dry white wine
For the Filling:
2 TBS olive oil
2 cups thinly sliced onions
3 TBS chopped fresh parsley leaves
2 pounds Swiss Chard or Beet Greens, leaves and stems roughly chopped
1 pound bacon
Kosher salt and freshly ground black pepper
1/4 cup freshly grated Gruyere cheese
4 oz bottle capers
1 large egg, beaten
1/4 cup light cream or milk
1 large egg yolk
2 TBS water
To prepare the pastry, combine the flour with the salt and pepper to taste in a large bowl or on a marble surface. Use your fingers or a pastry blender to cut the butter into the flour until it resembles coarse meal. Mound the flour mixture up and make a well in the center of it. Pour the remaining ingredients into the well. Slowly incorporate the liquid ingredients by working the flour into them a little at a time. When the dough comes together, compact it into a large disk, wrap it in plastic wrap and refrigerate for at least 30 minutes or up to one day.
To make the filling, warm the oil in a large skillet set over medium high heat. Add the onions and cook, stirring occasionally until soft but not brown, about 5 minutes. Stir in the parsley. Reduce the heat to medium and add the greens, capers and season with salt and pepper if needed. Stir to combine, and cook until the vegetables have softened and most of the liquid has evaporated, about 20 minutes. Remove from the heat and cool completely. (The filling may be prepared 1 day in advance. Cover and refrigerate. Return to room temperature before proceeding with the recipe.)
Stir the cheese, the beaten egg and the cream into the vegetable mixture. Set aside. Preheat the oven to 375 degrees F. Lightly grease a 10-inch Springform pan with butter and set aside.
Cut a quarter of the dough away from the disk and reserve in the refrigerator. On a lightly floured surface, roll the remaining three quarters of the dough into a 1/8 inch thick circle that will cover the bottom and sides of the Springform pan and come three quarters of the way up the sides. Line the pan with the dough.
Fill the shell with the vegetable mixture, patting it down with the back of a spoon so it is compact. Roll the remaining one-quarter of dough into a circle slightly larger than the pan. Place it on top of the filling. Use your fingers to crimp together the sides and top of the dough. Pierce the top of the tart with a fork to make tiny air vents.
Whisk together the egg and water. Brush this egg wash on the top and edges of the pastry. Bake until golden brown, about 1 hour. Allow to rest for 10 minutes before cutting.