In sauce pan over medium high heat, add all ingredients for chicken. Cook for 20 minutes. Remove chicken to a cutting board and shred or chop.
Preheat oven to 400degF.
In another sauce pan over medium heat, add butter, garlic powder, and cumin. Once melted, whisk in flour and cook for 2 minutes. Then add chicken broth and cook for 2 minutes. Next whisk in sour cream. Once combined, add jalapenos and cook for 5 minutes, stirring occasionally.
Ladle a thin layer of sauce into a 13x9 baking dish. Fill each tortilla with a portion of the cooked chicken and roll it up. Line tortillas up in the baking dish. Poor remaining sauce evenly over top of tortillas. Sprinkle with cheese. Bake in oven for 20 minutes. Sprinkle with scallions as soon as you remove from oven. Let sit at least 5 minutes before serving.