In a large pot, cover the skin, cores, and cinnamon stick with water and bring to a boil; reduce and simmer for 20 minutes
Drain the liquid into a large measuring cup and discarding the apple peel and cores (pick out the cinnamon stick and reserve for later.
Measure the liquid and add sugar to the ratio 2 cup liquid to 1/2 cup sugar
Return the simple syrup to the pot, add back the cinnamon and simmer for 30-40 minutes (the mixture will evaporate some of the water and leave the liquid a bit syrupy.
Remove from heat and cool for a few hours. Place in a bottle or canning jar and store in the refrigerator for up to two weeks.
