Step 1

Spray the slow cooker with no-stick cooking spray.

Step 2

Slice the potatoes into thin slices.

Step 3

Put about 1/3 of the potatoes in the bottom of the crockpot.

Step 4

Top with half the onion.

Step 5

Top that with half the ham.

Step 6

Repeat layers.

Step 7

End with the last of the potatoes.

Step 8

Whisk the evaporated milk and cream of celery soup together in a medium bowl.

Step 9

Add salt and pepper to taste.

Step 10

Pour the mixture over the potatoes.

Step 11

Cook on low for 8 hours.

Step 12

30 minutes before serving remove the cover, top with the cheese if desired, and replace the cover.