Preheat oven to 375 degrees. In a 13 x 9 inch baking dish, ladle in about ¾ cup of enchilada sauce so it covers the bottom of the dish.
In a large mixing bowl, stir in shredded chicken, 1 cup of the shredded cheese, green onions, salt, pepper, and garlic powder until combined.
In a medium bowl, whisk together the sour cream and enchilada sauce until smooth, creamy and combined.
Add 2 cups of the enchilada sauce to the chicken mixture and mix until the chicken is evenly coated.
Using a tablespoon, spread chicken mixture (about ¼ cup per tortilla) in the middle of the tortilla, like you would if you were making burritos. Roll the enchilada and place on baking dish. Repeat until you are out of chicken.
Top enchiladas with the rest of the enchilada sauce and 1 cup of cheese. Bake for 20-25 minutes, or until cheese is melted perfectly and bubbly. Garnish with green onions and sliced avocados (optional), enjoy!