Place the sweet potatoes in a large pot and cover with cold water. Bring to a boil, then reduce to a simmer. Cook until the potatoes are very tender, about 45 minutes. Drain the potatoes and let them stand to release any excess water, 10 to 15 minutes.
Combine the sweet potatoes, cream, butter, sugar, lemon zest, nutmeg and salt in a large bowl. Mash until the mixture is light and smooth. Serve with a pat of butter.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.