Heat the olive oil in a 12-inch cast-iron skillet over medium-high heat.
Season the chicken pieces with chili powder, cumin, smoked paprika, garlic powder, salt, and pepper. Add to the skillet and cook for 6 to 8 minutes, stirring occasionally, until browned on the outside and cooked through to 165 F / 74 C. Transfer to a plate.
Add the onion and bell pepper to the same skillet. Cook for 4 to 5 minutes, stirring, until softened and starting to brown at the edges.
Stir in the garlic and cook for 30 seconds until fragrant.
Return the chicken to the skillet along with the black beans, enchilada sauce, and chicken broth. Stir to combine and bring to a simmer.
Fold in the torn tortilla pieces. Simmer for 5 to 7 minutes, stirring occasionally, until the sauce thickens enough to coat the back of a spoon and the tortillas have softened.
Scatter the shredded cheddar or Mexican blend cheese evenly over the top. Cover the skillet and remove from the heat. Let it sit for 3 to 4 minutes until the cheese melts completely.
Top with cilantro, green onions, and avocado. Serve straight from the skillet with lime wedges on the side.