Place the cubed sweet potatoes in a large saucepan and cover with water. Bring to a boil and cook until potatoes are tender, around 10 minutes.
Strain the potatoes from the water and add them to a large bowl. Add the butter, brown sugar, salt, cinnamon, black pepper, and nutmeg to the bowl and mash with a potato masher until smooth.
Add the half and half and whisk until smooth and well combined.
Allow to rest for five minutes, then fluff the sweet potatoes with a spoon before serving.