Over medium heat, prepare a large fry pan or griddle large enough to accommodate grilling a 10-inch flour tortilla.
In a medium fry pan, heat the olive oil. Add the onion and peppers and cook until they start to soften. Stir in the cooked chicken and 1 cup Classic Marinara Pasta & Pizza Sauce. Set aside.
Working quickly, heat one side on the flour tortilla, then flip over and spread 1⁄4 of the chicken mixture over the tortilla. Sprinkle with 1 tablespoon of cheddar cheese and 1 tablespoon of Parmesan cheese.
Gently fold in half, and continue cooking and turning until the filling is hot and cheese is melted. Continue with each tortilla. Tortillas may be kept warm in a 200-degree oven before serving.
To serve, cut each quesadilla into wedges and serve with heated Classic Marinara Sauce for dipping.