HEAT oven broiler. Place rack 6 to 7-inches from heating element of oven. Lay chilies directly on oven rack. Broil 10 to 15 minutes or until chilies are brown and blistered, turning occasionally with tongs. Place chilies in bowl and cover with plastic wrap. Allow to rest 5-10 minutes. Peel skin, remove stems and seeds; chop.
HEAT oven to 350°F Coat 8 or 9-inch baking dish with no-stick cooking spray.
HEAT oil in large skillet on medium-low heat. Add onion and tortilla pieces. Cook 1 to 1 1/2 minutes or until onion is tender. Stir in chopped chilies and cheese. Whisk eggs, sour cream, adobo sauce and cilantro. Pour over pepper mixture. Stir to combine. Spoon into prepared baking dish.
BAKE 35 to 40 minutes or until knife inserted in center comes out clean. Serve warm.