Preheat oven to 350°. In a large bowl, combine the first 9 ingredients. Reserve 1 tablespoon feta for topping. Add remaining feta to spinach mixture. Add chicken; mix lightly but thoroughly. Transfer to a greased 9x5-in. loaf pan., Bake until a thermometer reads 165°, 60-70 minutes. Let stand 10 minutes before slicing. Serve with green onion and remaining 1 tablespoon feta.