Preheat grill to high heat. In a small bowl, mix the chili powder, paprika, onion powder, garlic powder, cumin, and salt.
Rub the spice blend evenly over the chicken. Coat with plastic wrap and chill for 10 minutes, allowing the flavors to combine.
Lay the chicken on the grill and lower the heat to medium (if it isn't possible to lower the heat, sear the chicken rapidly on both sides, and then move away from direct heat). Grill for 2-4 minutes per side, or until it is no longer pink in color and the juices run clear. Set aside for about 10 minutes, and then chop the chicken coarsely.
Preheat a medium non-stick skillet over medium heat. With an oven mitt, momentarily remove it from the heat, spraying with olive oil spray.
Place the tortilla in the pan, cooking for 30 seconds. Turn over the tortilla, uniformly spreading the cheese over half the tortilla. Top with the grilled chicken.
With a spatula fold the tortilla in half over the filling. Cook for 2 to 4 minutes, or until the bottom starts to brown and the cheese is melted. Slice into 4 wedges, serving immediately.