In a large skillet over medium-high heat, brown ground beef, bell pepper, and onion until the meat is no longer pink. Drain off excess grease.
Return meat to the skillet and stir in taco seasoning mix, green chiles, and water. Reduce heat, simmer, and cook for an additional 10 minutes, stirring frequently. Add corn and shredded cheese during the final 1-2 minutes of cooking.
Spoon beef mixture into a 9-inch deep-dish pie plate (or other 2-quart baking dish) that has been sprayed with cooking spray.
In a medium bowl, combine corn muffin mix, egg, and milk; mix well. Spoon batter over top of pie.
Bake for 22-24 minutes, or until top is golden brown and a toothpick inserted in the center of the cornbread crust comes out clean. If the topping starts to brown too quickly before it has cooked through, just cover the top lightly with foil and continue baking.
Let stand about 5 minutes before serving.
Notes
Use ground turkey, ground pork, ground chicken, or sausage in lieu of the beef.
If you don't have a deep-dish pie pan, use any other 2-quart baking dish.
Jazz up the filling with even more additions, such as sliced black olives, canned diced tomatoes or Rotel tomatoes with green chilies, or canned, drained pinto beans or black beans. You can also include extra seasoning, such as smoky ground cumin, oregano, paprika, or a bit of garlic.
Mexican cheese blends are convenient ways to add great flavor, but sharp cheddar cheese, Pepper Jack cheese, or other good melting cheeses will all work.