Apple Jalousie Tart

Name: Apple Jalousie Tart
Ingredients: 5 apples, such as Empire, McIntosh or Cortland, peeled, halved, cored, and cut into 8 wedges; ¾ cup sugar; 1 vanilla bean, seeds scraped; 3 tablespoons cognac; 1 teaspoon finely grated lemon zest, plus 2 tablespoons fresh juice; ¼ teaspoon kosher salt; 2 teaspoons unbleached all-purpose flour; 2 tablespoons unsalted butter, cut into small cubes; 1 sheet puff pastry, preferably all-butter, thawed if frozen; 1 large egg, lightly beaten; Sugar, for sprinkling; Vanilla ice cream, for serving (optional)