Spray the slow cooker with no-stick cooking spray.
Slice the potatoes into thin slices.
Put about ⅓ of the potatoes in the bottom of the crockpot.
Top with half the onion.
Top that with half the ham.
End with the last of the potatoes.
Whisk the evaporated milk and cream of celery soup together in a medium bowl.
Add salt and pepper to taste.
Pour the mixture over the potatoes.
Cook on low for 8 hours.
30 minutes before serving remove the cover, top with the cheese if desired, and replace the cover.
Storage:Store leftovers in an airtight container in the fridge for up to three days.Reheat leftovers the next day in a casserole dish in the oven at 350 degrees for 10 to 15 minutes. Or in the microwave for one to two minutes.Expert Tip: If you use thin skinned red potatoes or Yukon Gold potatoes you don't have to peel them. Just wash well and slice thinly.
Try to keep your potato slices as even as possible so that they cook at the same time.
Make slicing the potatoes easy, by using a mandolin if you have one.
Be sure to spray your slow cooker with nonstick cooking spray to easy clean up.
This is one of my favorite leftover ham recipes, and is a great way to use up ham slices from a holiday meal.
Cooking time can vary based on your slow cooker, make sure the potatoes are tender before serving.
If you are using a knife to cut your potatoes make sure that it very sharp so that you can get even slices.
Use freshly shredded cheese from a block instead of pre-shredded so that the cheese melts well.