You'll need about 1 large or 2 small sweet potatoes (roughly 1 lb) for 1 cup.
1. Peel and chop sweet potatoes into 2" chunks.
2. Bring a large pot of water to a boil. Add the sweet potatoes and boil until tender, about 13–15 minutes.
3. Drain the sweet potatoes and let them sit in the strainer for a few minutes to remove all excess water.
4. Transfer back into the pot and use a potato masher or potato ricer to mash until smooth.
5. Set aside and allow the mashed sweet potatoes to cool to room temperature before adding.