Heat a large skillet over medium heat. Add 1 tablespoon of olive oil. Once hot, add 1 thinly sliced onion and 2 sliced bell peppers (one red, one green). Cook until softened and slightly caramelized, about 8 minutes.

Remove the vegetables from the skillet and set aside.

Place a tortilla in the skillet, sprinkle a generous amount of shredded Monterey Jack cheese on one half of the tortilla. Top with some of the cooked onions and peppers.

Fold the tortilla over to cover the cheese and vegetables. Cook until the bottom is golden brown, about 2 minutes, then flip and cook the other side until golden brown and the cheese is melted.

Repeat with the remaining tortillas, cheese, and vegetable mixture.

Serve the quesadillas hot, cut into wedges. Accompany with guacamole and salsa for dipping.