Preheat oven to 350°. Coat a 12- x 8- x 2-inch baking dish with cooking spray. Sprinkle green chiles, Cheddar cheese, and Monterey Jack cheese evenly into baking dish.
Beat milk, baking mix, and eggs at low speed with an electric mixer until smooth. Stir in ricotta cheese; spoon mixture evenly over chiles and cheeses in baking dish.
Bake, uncovered, at 350° for 45 minutes or until a knife inserted in center comes out clean. Let stand 10 minutes before cutting.