Heat olive oil in a skillet over medium heat. Add chopped onions and sauté until soft, about 3-5 minutes. Toss in sliced bell peppers and stir for 2-3 minutes. Add minced garlic and cook for 1 minute.

Incorporate shredded chicken, sprinkle spices over the mixture, and stir well. Pour in salsa and heat through for an additional 3-4 minutes.

Lay a tortilla flat. Sprinkle cheese on one half, add chicken filling, and top with more cheese. Fold the tortilla in half.

Heat a non-stick skillet over medium-high heat. Cook quesadilla for 2-3 minutes until golden brown, then flip and cook the other side for 2-3 minutes until cheese is melted.

Remove from skillet, let cool for a minute, then cut into wedges. Serve with guacamole, salsa, or sour cream.