Sweet potato casserole is a familiar, comforting addition to holiday gatherings, offering just the right amount of sweetness to offset savory side dishes. But let's face it: it's one more thing to rob your oven of whatever space is left. So, here, the sweet potatoes are made in the slow cooker, saving oven space (and limiting meal-prep stress).
These sweet potatoes have just enough (read: plenty of) butter, heavy cream, and milk. Brown sugar and cinnamon play up the natural sweetness, but I also slip in a subtle ingredient that adds complexity: carrots.
It's important to stir the potatoes periodically during the cooking process, because you don't want anything to brown. The goal is to prepare the sweet potatoes and carrots by gently coaxing out a candied flavor—flavor that is further intensified by the leisurely cooking time (read more on how low temperatures enhance the sweetness of sweet potatoes here). If at any point the liquid level gets too low, add a bit more milk or heavy cream.
Then, whip them quickly until airy, taking care not to over-beat the mixture. I like to leave a little texture in mine, but if you prefer yours totally pureed, mash them a bit first and then proceed using a hand-held mixer.