Heat 1-tablespoon oil in a non-stick skillet over medium heat. Add the green onion and garlic and fry for 2 minutes. Than add the shredded chicken and chili powder. Toss until all ingredients are well coated with chili powder and chicken is warm. Remove from heat and add the salsa sauce, sliced olive, salt and pepper to taste. Stir well and set aside.
Preheat oven to 350 degrees F. Cut the bell peppers into 2-inch pieces and remove seeds. Press each piece open so the peppers are as flat as possible. Arrange close together in a single layer on a large baking sheet.
Spoon the chicken mixture evenly over pepper halves.
Top with cheddar cheese.
Bake nachos for 15 minutes, or until cheese has melted. Then remove from oven and top with chopped cilantro. Serve the chicken nachos immediately.