Grease the inside of your slow cooker with cooking spray or butter.
Peel (optional) and thinly slice the potatoes. Ensure slices are even for consistent cooking.
In a bowl, toss the potato slices with melted butter. Add Lipton Onion Soup mix, stirring to coat evenly.
If using cheese, mix it with the potatoes now.
Layer the seasoned potatoes in the slow cooker. Pour chicken broth or water over the top.
Cover and cook on low for 5-6 hours or high for 2-3 hours.
When potatoes are tender, season with salt and pepper.
Serve hot as a side dish.