Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13 inch baking dish.
In a large skillet over medium heat, cook chicken until no longer pink. Add Buffalo sauce, ranch dressing, cheddar cheese, mozzarella cheese, green onions, garlic powder, onion powder, cumin, salt and pepper. Stir to combine, and cook until heated through.
Fill each shell with the chicken mixture, and arrange in the prepared baking dish.
Bake in the preheated oven for 25 minutes, or until shells are tender.
Serve warm.
Interesting Facts
Buffalo sauce originated in Buffalo, New York in the 1960s.
Jumbo shells can be found in the pasta section of most grocery stores.
This dish can be made ahead of time and frozen for later.