Spray the inside of the slow cooker with cooking spray.
Layer half of the potato slices in the slow cooker.
Top with half of the shredded cheese, half of the bacon, and half of the green onions. Season with salt and pepper.
Add half of the butter slices evenly over the top.
Repeat the layers with the remaining ingredients.
Cover and cook on low for 6-7 hours, or until potatoes are tender.
Stir gently before serving to mix the melted cheese and flavors evenly.