Move oven rack to middle position and preheat oven to 400 degrees F. Spray 8-inch square pan with nonstick cooking spray; set aside.
In large bowl whisk together dry ingredients. In large measuring cup whisk wet ingredients until combined. Pour wet ingredients into dry ingredients and stir until just combined and no flour streaks remain (DO NOT OVERMIX!) Fold in green chiles and cheese.
Pour batter into prepared pan, smoothing into an even layer. Dot batter with pieces of butter. Bake 25-30 minutes, or until golden brown and toothpick inserted comes out clean. Move cornbread to wire rack and cool at least 20 minutes before slicing and serving.