Gather the ingredients, have a skillet ready, and a little bit of oil or butter if desired. You can heat them in a nonstick skillet without using oil/butter.
Heat a skillet over medium heat.
Place a tortilla in the skillet and add cheddar cheese, some thinly sliced apple, and more cheese on top (so the cheese "sticks" to both inner areas of the tortilla, which will help the apple stay put. (Alternatively, use one tortilla and fold it in half, which can be easier to flip)
Cook until golden on the bottom, and the cheese begins to melt. Use a lid if the cheese needs a little more help melting.
Flip and cook the other side until toasted, and the cheese is melted.
Remove from the skillet, slice into wedges, and serve.