Servings: 10. Split chile peppers lengthwise and remove seeds and pith. Spread chiles in a single layer in a greased 9x13-inch baking dish. Sprinkle Cheddar cheese, green onions, and 1-1/2 cups of the mozzarella cheese over chiles. In a bowl, beat eggs, milk, flour, and salt together until smooth. Pour over chiles and cheese. Bake in a 325 degrees oven for 50 minutes or until a knife inserted in custard comes out clean. Meanwhile, mix salsa with the remaining 1-1/2 cups mozzarella cheese. Sprinkle over casserole and return to oven for 10 minutes or until cheese melts. Let stand for 5 minutes before serving.