How do you suggest reheating these if making ahead?

This post (https://food52.com/blog/9048-mashed-potato-strategies) suggests reheating mashed potatoes in foil-covered casserole dish in a low oven until warm, and there are a couple suggestions in the comments as well, like using a double-boiler. Whatever method you choose, I'd plan to have extra coconut milk on hand if you need more moisture.