You can leave the skin on the apple for better nutrition but I prefer the texture of this recipe with it peeled.

You can thinly slice the apple rather than finely dice it but you will need to cook it for longer.  When I do this I typically add a little more water and cover the skillet to speed up the process.  You can dice the apples finely to cook quicker (this makes them easy to sprinkle overtop yogurt or ice cream). 

Feel free to add a sprinkle of apple pie spice too if you have that on hand.

I often double this recipe and mix in a Granny Smith apple to balance the sweet red apple with the tart Granny Smith flavor.  But you can do all red apples if you prefer.