Split chilies; rinse and remove seeds. Dry on paper towels. Arrange chilies on the bottom of an 11" X 7" X 1-1/2" bake dish. Top with cheeses. In a bowl, beat eggs; add milk and biscuit mix. Blend well; pour over cheese. Sprinkle with salt. Bake at 325 for 50-55 minutes or until golden brown. Serve with salsa. 8 servings.