In a large mixing bowl, combine the shredded chicken, half of the sour cream (½ cup), onion, corn, garlic powder, cumin, chili powder, salt, and pepper. Mix well to combine.
Spread ½ cup of green enchilada sauce evenly on the bottom of a 9x13 inch baking dish.
Take a flour tortilla and fill it with about ¼ cup of the chicken mixture. Roll it up and place it seam-side down in the baking dish. Repeat with the remaining tortillas.
Once all tortillas are placed in the dish, pour the remaining ½ cup of green enchilada sauce over the top of the enchiladas.
Spoon the remaining ½ cup of sour cream over the sauce and sprinkle evenly with shredded Monterey Jack cheese.
Bake in the preheated oven for 25-30 minutes, or until the cheese is melted and bubbly.
Remove from the oven, allow to cool slightly, then garnish with chopped fresh cilantro.