In a large pot, bring 4 cups of water to a boil.
Add the yam chunks and cook until tender, about 15-20 minutes.
Drain the yams and return them to the pot.
Using a potato masher or fork, mash the yams until smooth. You can also use a blender for a finer texture if desired.
Add sugar, ground cinnamon, ground nutmeg, and salt to the mashed yams. Stir well to combine.
Gradually add milk or coconut milk, stirring continuously, until the porridge reaches your desired consistency.
Place the pot back on the stove over medium heat and cook for another 5-10 minutes, stirring occasionally, until the porridge is hot and has thickened to your liking.
If using, stir in the butter or margarine for added richness.
Enjoy your meal!