Rub the taco seasoning on both sides of the chicken breast filets.

Heat the olive oil over medium-high heat in a large, 12-inch skillet (an enameled cast iron works great, but is not required). Cook the filets for 5 minutes on each side or until the juices run clear or an instant read thermometer registers the chicken at 165°F on the thickest part of the chicken.

Remove the filets from the skillet, and pour in the salsa to deglaze the pan. Return the chicken filets to the skillet and cook for 5 minutes or until the salsa starts to reduce.

Lower the heat and sprinkle the cheese on top of each filet. Cover the pan with a large lid for 2-3 minutes or until the cheese has melted on top, and remove from heat.

Sprinkle with fresh chopped cilantro, if desired, and serve immediately.