Heat the olive oil in a large skillet over medium heat. Once it's hot, add the peppers and onion to the skillet. Cook, stirring often, for 5-7 minutes, until everything is softened. Then add the ham and cook another 3-5 minutes to get some color on the ham. After that, remove the skillet from the heat and pour out the ham mixture into the prepared pan. Sprinkle the cheese evenly over the top.