Preheat oven to 400.
Combine 1/4 cup cheese and next 7 ingredients (through chiles) in a large bowl, stirring just until moist. Pour mixture into a 13x9-inch baking dish coated with cooking spray.
Bake at 400 for 15 minutes or until set. Pierce entire surface liberally with a fork; pour enchilada sauce over top. Top with chicken; sprinkle with remaining 3/4 cup cheese. Bake at 400 for 15 minutes or until cheese melts. Remove from oven; let stand 5 minutes. Cut into 8 pieces; top each serving with 1 tablespoon sour cream.
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