1. Position the rack in the center of the oven and heat the oven to 400 degrees . If you're using a pizza stone, warm it on the rack for 30 minutes.
2. Lightly flour a large baking sheet or a pizza peel, then place the dough on top. Dimple and stretch the dough to fit your baking surface.
3. In a medium bowl, toss the chicken with the olive oil and five spice powder, then set it aside. Use a pastry brush or large spoon to spread the hoisin sauce over the dough, laving a 1/2-inch border. Scatter on half the cheese, then add the seasoned chicken. Sprinkle on the remaining cheese and the sesame seeds.
4. Bake the pizza until the crust is brown and the cheese has melted and is beginning to bubble, about 25 minutes. Let the pie cool for 5 minutes before topping it with the scallions.