Put chicken into an ovenproof dish, add sesame oil, soy sauce, garlic, chili powder, scallions and black pepper to taste.Mix well, cover, and chill overnight.
Preheat oven to 350 degrees. Uncover chicken and bake 30 minutes. Reduceheat to 275 degrees and cook 40 minutes more. Meanwhile, cook noodles according to package directions. Drain, then serve chicken and noodles, sprinkled with sesame seeds, if using.