In large bowl, mix together shredded chicken, 4 chopped green onions, sour cream, and 1/2 pound of grated cheddar cheese; set aside. Pour tomato sauce in bottom of 13x9 inch pan.
Fill tortillas with approximately 3-4 tablespoons of chicken mixture and roll, placing seam side down in pan with tomato sauce. Repeat until pan is full. Pour enchilada sauce over tortillas.
Cover with remaining grated cheese. Bake at 350 degrees until hot, 20-30 minutes. Remove from oven and top with remaining chopped green onions.