Peel and cut the sweet potatoes into evenly sized chunks, roughly 1-2 inches. Place them in a large pot and cover with water.

Bring the pot of water to a rolling boil over high heat, then reduce to medium and let simmer for 15-20 minutes until fork-tender.

Drain the sweet potatoes in a colander and let steam for a few minutes to evaporate excess moisture.

Return the sweet potatoes to the pot and mash until smooth using a potato ricer or hand masher.

Add the warmed half-and-half or milk and butter to the mashed sweet potatoes, mixing until creamy. Season with salt and black pepper.

Transfer the mashed sweet potatoes to a serving bowl or platter and sprinkle with cinnamon if desired.