Peel the sweet potatoes
Cut them into even chunks
Place the chunks in a pot and cover with cold water
Add a pinch of salt
Bring to a boil
Reduce to a simmer
Cook until the sweet potatoes are very tender
Drain the water well
Return the sweet potatoes to the pot
Mash with a potato masher or fork
Add butter
Add milk or cream a little at a time
Add salt to taste
Add black pepper if desired
Mix until smooth and creamy
Serve warm