Heat a cast iron girl on high heat. Meanwhile, marinate the chicken breast in the garlic powder, chili powder, paprika, 1 tbsp of oil, and salt and pepper. Rub the chicken to evenly distribute the spices. Brush the grill with oil and once hot, cook the chicken on both sides until cooked through. Set aside when cooked.
Heat 2 tbsp oil in a medium saucepan over medium heat. Add the diced onions and garlic and cook for 3 minutes. Add the diced bell peppers and cook for another 5 minutes.
Add the canned diced tomatoes and black beans. Bring it to a boil then down to a simmer. Let it simmer for 30 minutes. Season for salt and pepper.
Dice the cooked chicken in bite size pieces. Mix half of the chicken with the chili mix and leave the other half to top the Frito pie with.
You can serve the Frito pie in individual packs of Frito corn chips or in a baking dish. Top with shredded cheese, tomatoes, and sliced scallions.