Sprinkle some finely shredded cheese on the pan slightly smaller than the piece of bread (the cheese expands as it melts) no need for extra oil or anything since the cheese is fatty enough. Toss the bread on top and let the magic happen. You’ll know it’s good and crispy when you can get your spatula/flipping utensil under the cheese without it squishing up or sticking to the pan. If either of those things happen, just give it a little more time