In medium skillet, cook ground beef and onion over medium-high heat until beef is no longer pink; drain. Stir in salsa, taco seasoning mix and water; bring to a boil. Reduce heat to low; cook for 5 to 6 minutes or until mixture is thickened. Stir in corn. Spoon into ungreased 8-inch square baking dish. Prepare batter for corn muffins according to package directions. Stir in cheese and chiles until smooth; spread over meat mixture. Bake, uncovered, in pre-heated 350 degree oven for 30 to 35 minutes or until crust is golden brown. Top with additional salsa, if desired.