Preheat the oven to 180°C.
In a large bowl, combine the coarse maize meal and salt.
Gradually add warm water, mixing until a thick, stiff batter forms. It should be moist but not runny.
Stir in the oil or butter if using.
Grease a baking dish and press the mixture firmly into it, smoothing the surface.
Cover tightly with foil.
Bake for 60–75 minutes, until fully cooked and firm throughout.
Remove the foil for the last 10 minutes if you prefer a slightly drier top.
Allow to cool slightly before slicing and serving.