Heat oven to 400°F. Spray 9-inch glass pie pan with nonstick cooking spray. Slit chiles lengthwise; remove seeds. Arrange chiles in single layer in bottom and up side of pie pan. Sprinkle 1 cup of the cheese over chiles.
Beat eggs in medium bowl with wire whisk. Add baking mix, garlic powder and milk; beat until well blended. Pour over cheese.
Bake at 400°F. for 25 to 30 minutes or until knife inserted in center comes out clean. Sprinkle with remaining 1/2 cup cheese. Let stand 5 minutes before serving. Serve with salsa and, if desired, sour cream.