Preheat oven to 350°F. Coat a 9-by-13-inch (or similar-size) baking dish with cooking spray.
Thinly slice 1/4 cup scallion greens; set aside. Mince the whites. Whisk the scallion whites, hoisin sauce, soy sauce, ginger, garlic, hot sauce and five-spice powder in a large bowl. Add chicken and toss to coat. Arrange the chicken in an even layer in the prepared baking dish, meatier-side down. Pour any remaining sauce from the bowl over the chicken
Bake, turning once halfway so the meatier side is up, until an instant-read thermometer inserted into the thickest part without touching bone registers 165°F, about 1 hour. Transfer the chicken to a serving platter and top with any remaining sauce from the baking dish. Sprinkle with sesame seeds and the reserved scallion greens.