Preheat oven to 350º.
Grease a 9x13” glass baking dish; set aside.
In a Dutch oven, brown the beef, onion and bell pepper over medium heat.
Cook until beef is no longer pink.
Use a hamburger chopper to chop the ground beef into small pieces while frying.
Drain off any grease.
Stir in tomatoes, beans, corn, tomato sauce and taco seasoning.
Bring ingredients to a boil.
Reduce heat and simmer, uncovered, for about 30 minutes. (Mixture will be thin).
Layer 3 cups of Doritos chips in the bottom of baking dish.
Spoon 4 2/3 cups beef mixture over top of Dorito chips.
Sprinkle beef mixture with 1 ½ cups cheddar cheese.
Repeat layers once.
Top casserole with 3 cups of Nacho Doritos Chips.
Top with 2 cups of cheese.
Bake, uncovered at 350º for 15-20 minutes, or until casserole is golden brown.
Garnish casserole with sliced green onions, if desired.