Slice the yellow onions into thin strips and heat the olive oil in a large non-stick skillet over medium heat. Add the sliced onions and sauté until golden brown and caramelized, about 15-20 minutes.

Once the onions are caramelized, sprinkle in the cumin seeds, coriander powder, and smoked paprika. Stir well and allow the spices to release their aromas for 2-3 minutes.

Take a tortilla, layer a generous amount of cheese on one half, and add spiced onions on top. Fold and press down gently.

In the same skillet, add more oil if necessary and heat over medium-high. Cook the filled tortillas for 3-5 minutes or until golden brown, then flip and cook for another 3-5 minutes.

Remove the quesadillas from the skillet, let them rest for a minute, slice into wedges, and serve warm with salsa or guacamole.