Preparation

• Put the peaches in a large bowl, and toss with the thyme. In a small bowl, combine the bourbon with the vanilla bean seeds, and then toss with the peaches. In another small bowl, whisk the granulated sugar and cornstarch. Sprinkle over the peaches and toss to combine. Cover and set aside.
• Line a large rimmed baking sheet with parchment. Place a rack in the lower third of the oven and heat the oven to 425°F.
• On a lightly floured surface (or on a sheet of parchment), roll the dough into an 18×20-inch rectangle. Put the prepared baking sheet on a work surface so that a long side is facing you. Roll the dough onto the rolling pin, and gently unfurl it onto the baking sheet, placing it so that the width of the dough extends just to the inside edges of the pan and the length of the dough extends over the long edges of the pan by about 3-1/2 inches on each side.
• Spoon the filling onto the dough, leaving a 3-inch border on each short end. Gently fold the dough hanging over one long edge of the pan over the top of the filling, placing it about 2 inches past the center. Lightly brush water on the edge of the dough on top of the filling. Fold the remaining long edge of dough over the filling so that it overlaps the dough on the filling by about 2 inches. Brush the seam lightly with water and press gently to adhere. Brush the open ends of dough lightly with water and crimp to seal. Cut 1- to 1-1/2-inch-long diagonal slits on top of the pie to vent.
• In a small bowl, whisk the egg and cream. Brush the pie with the egg wash. Sprinkle the top with turbinado sugar. Transfer the pie to the oven. Bake until the crust is golden brown and the filling is bubbly, about 35 minutes. Rotate the pie halfway through baking for even browning; tent with foil if the pie is browning too quickly.
• Cool for at least 15 minutes before serving.