1. Preheat your oven to 400°F (200°C).
2. In a large skillet, melt butter over medium-high heat; cook chicken with onion, red pepper, chili powder to taste, oregano and salt, using a fork to break up meat, for about 5 min or until chicken is cooked through.
3. Stir in beans, corn and salsa.
4. Whisk milk with flour. Gradually stir the milk mixture into the chicken mixture. Bring to a boil, then stir frequently for 2 min.
5. Remove from heat; stir in 1 cup (250 mL) of the cheese.
6. Transfer into an 8-inch (2 L) square dish.
7. Sprinkle chicken with tortilla chips, then the remaining cheese.
8. Bake for 10 min or just until cheese is melted.
9. Let stand for 5 min before serving.
10. Scoop out into bowls. Serve with additional salsa, sour cream and guacamole.