Preheat oven to 350 degrees. In bowl, whisk egg and 1 tbsp. five-spice powder. Put nuts in another bowl. Dip chicken in egg, then in nuts. In skillet, fry in oil over medium, 2 minutes per side. Bake on a foil-lined baking sheet until golden, 8 minutes. In bowl, whisk oyster sauce, 1/2 tsp. five-spice and 3 tbsp. water. Top rice and chicken with scallions and serve with sauce.