Peel and core apples and chop into larger chunks. Core pears and chop into same size pieces as apples. (I keep the skin of the pear on, you can keep the apple skin on too if you prefer)
Add to a slow cooker, top with cinnamon and sugar. Stir in water.
Set on low for 8 hours or high for 4 hours. Do not open the slow cooker while it is doing it's business.
When finished run a fork through the apples and pears. They will just fall apart and this will yield a chunky apple, pear sauce. If you like it smoother, transfer to a blender and blend until you reach desired consistency.
Notes
You may need a little bit less water depending on how large your apples are. For reference I used 10 medium to large apples