Heat 1 tablespoon olive oil in a stainless steel skillet over medium high heat.
Add the pepper and onions to the skillet. Cook the vegetables until softened and beginning to char.
Stir in the garlic and jalapeno (if using). Cook for 1 minute. Transfer the vegetables to a bowl and wipe the skillet clean.
Add an additional 1 tablespoon olive oil to the skillet and return to the heat. Add the chicken to the pan with 2 tablespoons water. Stir in the fajita seasoning and heat through, approximately 4-5 minutes.
Transfer the chicken to a separate bowl and set aside. Wipe the skillet clean.
Brush one side of each of the tortillas with canola oil to coat lightly.
Return the skillet to the heat and place one tortilla in the pan. Sprinkle half the tortilla with 2 tablespoons shredded cheddar, 1/4 of the vegetables, 1/4 of the chicken and then top with 2 tablespoons shredded colby jack.
Fold the unfilled side of the tortilla over the quesadilla filling and place a second tortilla in the pan. Repeat with the filling layers and then fold the tortilla over the quesadilla filling of the second tortilla.
Cover and cook for 3-4 minutes or until the tortilla is golden and crispy on the bottom. Carefully flip the quesadillas over and cook for an additional 3-4 minutes. Repeat with the remaining tortillas and filling.
Cut the quesadillas into quarters and serve with chopped green onions, cilantro, jalapeno, sour cream and salsa, if desired.