Place peeled and cubed sweet potatoes in a large pot and cover with water.
Bring to a boil, reduce heat, and simmer for 20–25 minutes until fork-tender.
Drain thoroughly and return potatoes to the pot to release excess steam.
Add butter, cinnamon, nutmeg, and salt.
Using a hand blender or hand mixer, whip while slowly adding milk until smooth and fluffy.
Taste and adjust seasoning. Serve warm.