Preheat oven to 350 degrees.
Melt butter in a medium saucepan over medium heat. Add onion and jalapeno and cook 2 to 3 minutes.Add flour and cook and stir for 1 minute. Gradually whisk in the chicken broth. Bring to a boil and simmer for 2 to 3 minutes.Add the cream cheese and stir until melted.
Remove from heat and stir in the sour cream, salt, cumin, garlic powder, oregano, black pepper, and green chiles.
In a medium bowl, combine chicken, green onion, and black beans.
Arrange 1/3 of the tortillas in the bottom of a greased 9x13-inch baking dish. Overlapping as needed.
Spread half the chicken mixture on top of the tortillas. Pour 1/3 of the sauce evenly over the chicken and sprinkle with 1/3 of the cheese.
Repeat another layer of tortillas, chicken, sauce, and cheese, (using half the remaining tortillas, sauce, and cheese and all the remaining chicken mixture.)
Top off with remaining tortillas, sauce and cheese.
Bake uncovered for 35 minutes. Garnish with green onion and cilantro if desired.