Chorizo sausage adds a kick to these stuffed quesadillas.
To save time, any cooked shredded chicken can be used instead of starting from scratch,  In that case, decrease the taco seasoning to the 1 tsp. used on the veggies. Try substituting a large serrano or jalapeno pepper that has been seeded and sliced for the red bell pepper.
Starting with a cold griddle insures that the filling will be warmed by the time the quesadillas have browned.

1 8-oz skinless boneless chicken breast half
2 teaspoons olive or canola oil, divided
2 teaspoons taco seasoning mix, divided
1 small link fresh chorizo sausage, about 2 1/2 ounces
1/2 small onion, sliced
1/2 small red bell pepper, sliced 1/4″ thick
4 ounces crimini mushrooms, sliced
3 ounces pepper jack cheese, shredded
2 8-inch whole wheat tortillas
2 teaspoons butter, softened

1. Rub the chicken breast with 1 tsp. of oil, then season on both sides with 1 tsp. of the taco seasoning mix. Wrap tightly in plastic and refrigerate for 30 minutes.
2. Meanwhile, microwave the onion, bell pepper, and mushrooms each separately until barely tender and set aside.
3. Remove the chicken from the refrigerator about 10 minutes before cooking and slice into 1/4″ strips.
4. Crumble the chorizo into 1/2 inch pieces in a large non-stick skillet over medium heat. Cook until barely browned but cooked through. With a slotted spoon, remove to a paper towel lined plate, leaving the drippings behind.
5. Warm 1 tsp. of oil along with the sausage drippings. Add the chicken and sear on both sides until golden and just cooked through. Remove to a separate plate.
6. In the same skillet, heat the remaining tsp. of oil. Add the onion, bell pepper, and mushrooms and toss to coat with oil. Season the veggies with the remaining taco seasoning and stir-fry until heated through. Return the chicken and chorizo to the skillet to warm, then set aside.
7. Sprinkle half of the cheese evenly over each tortilla. Pile half of the chicken mixture onto the bottom half of each tortilla, then fold the top half over all the filling to close.
8. Spread the quesadillas with some of the softened butter and place buttered side down on a cold griddle, then spread the remaining butter on the top sides.
9. Cook over medium low heat, turning once, until the quesadillas are golden brown, the cheese has melted, and the filling has heated through.