Cut slits on the top of the pork loin about 1-inch down into the meat.
Plug apple slices into the slits; set aside.
Place the onions and remaining apple slices down in the crock pot.
Using the 1/2 cup butter slices, add a layer of butter over the onions and apple slices.
Add the pork loin.
Sprinkle the pork with the salt, pepper and cinnamon.
Add the thyme.
Drizzle the honey over the pork loin and spices.
Cover and cook on low for 6 hours without opening the lid during the cooking time.
When the cooking time is done, remove the pork onto a platter and let rest for at least 5 minutes; slice and serve.
