Place large skillet over medium heat then add oil or butter. When oil is hot or butter has melted, add sliced bell peppers, sliced onion, garlic, salt and pepper. Cook veggies for about 5–6 minutes, stirring occasionally until onions are translucent and peppers are crisp tender. You may cook the veggies longer if you prefer them a bit softer. Transfer veggie mixture to a bowl then set aside.

Wipe out the skillet then return to medium-low heat. Allow a few seconds to pass so the skillet can return to temperature then lightly coat with cooking spray. Alternatively, you can also brush a very light amount of butter onto the bottom of the pan. Place a tortilla into the skillet then immediately add ½ cup of shredded cheese to cover one half of the tortilla. Spread roughly 1/6th of the veggie mixture on top of the cheese then fold the uncovered half of tortilla on top of the veggies and cheese.

Press down on the quesadilla with a spatula to force cheese and veggies into contact with heat and seal top and bottom together with the filling. Let tortilla to cook on the first side for about 2–3 minutes (depending on temperature), until golden brown and crispy.

Flip quesadilla then cook for 2–3 minutes until golden brown and crispy on the opposite side. If the tortilla becomes too brown before the cheese melts, lower the temperature. The objective is for the cheese to be completely melted and gooey at the same time the tortilla becomes golden and crispy. Generally, if you have the patience for it, lower heat is better.

Transfer the quesadilla to a cutting board, cut into wedges then serve with plenty of salsa, sour cream and guacamole. Enjoy!