Adjust oven rack to middle position and heat oven to 450 degrees. Grease a 9" pie plate. Press tortilla into prepared pie plate and spray lightly with cooking spray. Shred chicken and toss with cilantro, green chilis, 1 cup cheese, 1/2 tsp. salt, and 1/2 tsp. pepper in large bowl until combined. Spread filling over tortilla.
Whisk eggs, milk, flour, baking powder, and 1/2 tsp. salt in bowl until smooth. Slowly pour over filling, then sprinkle with remaining cheese. Bake until surface is golden brown; approximately 20 minutes. Let cool 5 minutes. Cut into wedges and serve.
10" flour tortillas are sometimes called "Burrito" size. You will need the 10" for sure as this serves as the crust. ENJOY!