Heat oven to 400°F. Coat 13"x9" baking dish with cooking spray.
In bowl, combine chicken, 1 cup cheese, beans, ½ cup sauce, half of scallions, lime zest and juice and chili powder.
Arrange tortillas on clean work surface. Divide chicken mixture evenly among tortillas, placing filling down center of each; roll up to enclose filling.
Place enchiladas, seam side down, slightly touching, in baking dish. Top with remaining sauce and 1 cup cheese.
Bake until hot and bubbly, 20–25 min.
If desired, dollop with sour cream and guacamole and sprinkle with onion.
