Preheat your oven to 400°F. Line a baking sheet with parchment paper. Using a fork, prick the clean sweet potatoes in a few spots, then place on the lined baking sheet. Bake until tender when pierced with a fork, about 45-60 minutes, depending on their size.
When the sweet potatoes are cool enough to handle, peel off the skin.
In a medium pan over medium-low heat, mash the peeled sweet potatoes with a potato masher. Add the coconut milk as you mash, starting with ¼ of the can and adding more as needed.
Season the mashed sweet potatoes a few pinches of cinnamon and salt and pepper, to taste.
Serve immediately, garnished with fresh chives, if using. Or refrigerate until ready to serve. The mashed sweet potatoes can be reheated over medium-low heat. Add some of the extra coconut milk, as needed.
I recommend using full-fat unsweetened coconut milk that comes in a can. While you can use canned lite coconut milk, it's quite watery and won't result in the same consistency. On the other side of the spectrum, canned coconut cream will be too thick for this recipe.
Shake the can before opening it and gently stir it once open to mix the cream on top into the milk.
Transfer the unused coconut milk to a glass storage container with a lid and refrigerate it for up to 5 days or freeze it for up to 3 months. Defrost it in the refrigerator overnight before using.
Storing:Leftovers can be covered and refrigerated for up to 5 days. I do not recommend freezing for best results.