In a medium mixing bowl, combine the cooked chicken breast, shredded cheese, ranch dressing, diced green onions, diced bell pepper, and black pepper. Mix well until evenly coated.

Place a non-stick skillet on the stove and heat it over medium heat. Add a tablespoon of olive oil and let it warm until shimmering.

Take a flour tortilla and lay it flat in the hot skillet. Spoon a generous portion of chicken and cheese mixture onto one half of the tortilla. Fold the tortilla over to cover the filling.

Cook the quesadilla for about 3-4 minutes, or until the underside is golden and crispy. Flip and cook the other side for an additional 2-3 minutes until the cheese has melted.

Remove the quesadilla from the skillet and let it rest on a cutting board for 2 minutes before slicing into wedges.

Continue the process with the remaining tortillas and filling mixture, adding more olive oil to the skillet as necessary.