These are a great side dish to make ahead up to a day in advance. Follow the recipe as written and let the potatoes cool completely. Then, transfer them to an airtight container and store the container in the fridge. When you're ready to cook, add the potatoes back into the slow cooker and reheat over low heat until smooth and creamy. You may need to splash in more milk loosen them up. Sprinkle with more cheese, bacon and chives before serving.