Preheat the oven to 375°F (190°C).
Heat olive oil in a skillet over medium-high heat. Brown the chicken strips on both sides, about 5–6 minutes. Remove and set aside.
In the same skillet, sauté the sliced bell peppers and onions for 5–7 minutes, or until softened.
Combine chili powder, paprika, cumin, garlic powder, onion powder, salt, and pepper in a small bowl. Sprinkle over the cooked vegetables. Return the chicken to the skillet and toss to coat.
Transfer the chicken and vegetable mixture to a 9×13-inch baking dish. Spread salsa over the top, then sprinkle with the shredded cheese.
Bake for 15–20 minutes, or until the cheese is melted and bubbly. Serve hot, garnished with sour cream and fresh cilantro if desired.