In a large pot, bring the water to a boil. Add the salt and sugar (if using).
Gradually stir in the maize meal, whisking continuously to prevent lumps.
If using, stir in the grated pumpkin or butternut squash.
Reduce the heat to low and cook the mixture, stirring frequently, for about 15-20 minutes, or until it thickens and the maize meal is fully cooked.
Stir in the milk or cream if desired, for added creaminess.
Transfer the Sitfubi to a serving dish. Let it cool slightly before slicing or serving.
Enjoy your meal!