In a small heavy saucepan, bring the water, salt and cayenne to a boil. Reduce heat to a gentle boil; slowly whisk in cornmeal. Cook and stir with a wooden spoon for 15-20 minutes or until polenta is thickened and pulls away cleanly from the sides of the pan.
Meanwhile, in a large skillet, cook the beef, onion, green pepper and garlic over medium heat until meat is no longer pink. Stir in the beans, enchilada sauce, chilies, olives, chili powder and cilantro; heat through.
Spread polenta into a greased 8-in. square baking dish. Top with meat mixture. Cover and bake at 350° for 25 minutes. Sprinkle with cheese. Bake, uncovered, for 2-5 minutes or until filling is bubbly and cheese is melted.