Note that if you prefer, you can put the sweet potato through a blender or food processor to make the mixing of the batter easier. But it's not absolutely needed. You can achieve a decent texture by mashing with a fork if necessary. Also remember, if your baking pan is thinner than a typical casserole dish, shorten your cooking time to 20 minutes, and check it every 5 minutes after that. As with most baked goods, a knife should pull out clean when it is done baking. It will look a bit moist, but it shouldn't pull any batter out.
Whisk together all the ingredients in a large mixing bowl, making sure to mash up the sweet potato as much as possible. The batter should be thick when fully mixed.
Transfer to a baking dish and smooth the thick batter out as evenly as possible of your baking dish.
Bake for 30 minutes, then remove from oven and allow to cool completely. These are best if chilled in the fridge overnight, but it's not absolutely necessary. Just note they will be very soft if eaten right after baking. Sitting allows them to solidify completely.
Cut into 8 pieces and serve.
Please note that the nutrition data given here is a ballpark figure. Exact data is not possible.