Combine shredded chicken, cream cheese, 1/4 cup green enchilada sauce, 1 cup of shredded pepper jack cheese, crushed red pepper flakes and garlic powder.
Evenly distribute filling between 6 and 8 tortillas. Roll them up and place them in a greased 9" x 13" casserole dish.
Melt butter in a small saucepan over medium heat.
Whisk in flour and taco seasoning.
Add 1.5 cups of chicken broth and remaining enchilada sauce and whisk until combined and smooth.
Stir in 1 small can of green chiles and 1/2 cup of shredded pepper jack cheese. Mix until cheese is fully melted.
Remove from heat and stir in 1 cup of sour cream.
When sour cream is completely incorporated, pour the sauce over prepared enchiladas.
Sprinkle with remaining 1/2 cup shredded pepper jack cheese and diced jalapeño.
Bake 350° for 25 minutes until sauce is bubbling and cheese is browning.