Preheat oven to 375°. In a large skillet, cook beef and onion over medium heat until meat is no longer pink; drain. Stir in tomato sauce, corn, water and sloppy joe seasoning; cook over medium heat until bubbly. Reduce heat and simmer for 5 minutes; remove from heat and set aside. , Separate biscuits; flatten each to a 3-1/2-in. circle. Place milk and cornmeal in separate shallow bowls; dip both sides into milk and then into cornmeal. Place seven biscuits around the sides and three on the bottom of an ungreased 9-in. pie plate. , Press biscuits together to form a crust, leaving a scalloped edge around rim. Sprinkle with 1/2 cup cheese. Spoon meat mixture over cheese. , Bake until crust is deep golden brown, 20-25 minutes. Sprinkle with remaining cheese and, if desired, fresh parsley. Let stand 5 minutes before serving.