Preheat the oven to 375°. In a small bowl, mix the first 4 ingredients. In a large bowl, whisk the eggs. Whisk in the pumpkin, evaporated milk, and the sugar-and-spice mixture. Sprinkle dried cranberries on the bottom of the piecrust. Gently pour pie filling into the piecrust. Bake until just set in the center, about 1 hour; let cool completely on a wire rack. Top the cooled pie with orange zest. Serve with whipped cream, if using.