Place the diced sweet potato in a steamer and steam until soft enough to mash (roughly 10 mins).
Once the sweet potato has cooled, add it to a bowl and mash with a fork until there are no lumps.
Add the remaining ingredients (excluding the cacao nibs), and mix really well until the mixture is smooth and fluffy. You can use a handheld mixer to make it easier if you prefer.
Add the sea salt if desired for taste.
Split the mixture between 2 glasses, top with the cacao nibs and place in the fridge for a few hours to set. They can be left overnight if required.