In a large mixing bowl, combine the shredded chicken, buffalo sauce, green onions, ranch dressing, onion powder, garlic powder, and black pepper. Stir until thoroughly mixed.
Heat ½ tablespoon of butter in a large nonstick skillet over medium-high heat. Work in batches to avoid overcrowding.
On one half of a flour tortilla, layer ¼ cup of shredded cheese, followed by ½ cup of the buffalo chicken mixture, and then another ¼ cup of shredded cheese. Fold the tortilla in half to enclose the filling.
Place the folded tortilla into the hot skillet and cook for 1 to 2 minutes on each side, or until the cheese is melted and the exterior is crisp and golden. Repeat the process with the remaining tortillas, adding more butter as needed.
Slice and serve warm. Accompany with sour cream, Mexican crema, or extra ranch dressing as desired.