Preheat a conventional oven to 350 degrees F. Lightly butter a large cast iron skillet or 9 x 13-inch casserole dish.
In a large bowl, mix together the cream cheese, sour cream and mayonnaise until blended.
Whisk in the bell pepper, jalapenos, red onion and green chilies. Whisk in the cheese and corn. Salt and pepper, to taste.
Spread the mixture into the cast iron skillet or casserole dish. Sprinkle with chili powder, to taste.
Bake for 30 minutes or until bubbly and hot throughout. Let cool slightly. Top with green onions if desired, and serve with chips or as a side dish.