Before I even turn on the stove, I grate my cheese fresh and mix the cheddar and Monterey Jack in a small bowl. This little step makes a huge difference in texture. I also chop the green onions here if I'm adding them, keeping everything within arm's reach of the stove.
I place my non-stick skillet over medium heat and let it warm up for about a minute. A properly heated pan is the secret to that golden, crispy tortilla shell. I add a small swipe of butter or oil to coat the surface lightly before the tortilla goes in.
I lay one tortilla flat in the pan and scatter the cheese mixture evenly across half of it, leaving a small border. This is where my kids love to help, sprinkling the cheese like confetti. If using green onions, I add them now, right on top of the cheese.
Once the cheese starts to soften and the tortilla edges begin to bubble, I fold the bare half over the cheesy half using my spatula. I press down gently so everything sticks together as it continues cooking for another minute.
I carefully flip the folded quesadilla to brown the other side. This usually takes about one to two minutes. I keep an eye on the color, since every stove heats a little differently, and I don't want it burning before the cheese fully melts.
I transfer the quesadilla to a cutting board and let it rest for a minute before slicing it into wedges. This short rest keeps the molten cheese from spilling out the moment I cut into it, which my kids really appreciate.