1. Preheat the oven to 375°F.
2. In a medium bowl, toss the chicken, lime juice, and salt and pepper to taste together and set aside.
3. In a large skillet, heat 2 tablespoons of the oil over medium heat. Saute the bell and jalapeno peppers until crisp-tender, about 5 minutes. Transfer to a small bowl. Heat the remaining tablespoon of oil in the same skillet over medium heat and cook the garlic, cumin, and chili powder, stirring, about 2 minutes. Stir in the beans and cook, stirring, until heated through, about 3 minutes.
4. In a shallow 3-quart baking dish or casserole, layer one half of the chips, pepper mixture, beans, chicken, and cheese. Repeat layering with the remaining chips, pepper mixture, beans, chicken, and cheese. Stir the scallions and cilantro together and sprinkle over the top. Bake until the cheese is melted, 10 to 12 minutes. Serve with hot sauce and salsa, if desired.