Wash and peel the sweet potatoes.
Cut them into evenly sized chunks or cubes. This ensures they cook evenly.
Place the sweet potato chunks in a large pot and cover them with cold water.
Add a pinch of salt to the water.
Bring the water to a boil over high heat, then reduce the heat to medium and let the sweet potatoes simmer for about 15-20 minutes, or until they are fork-tender. You should be able to easily pierce them with a fork.
Drain the cooked sweet potatoes in a colander.
Transfer them to a mixing bowl or the pot you cooked them in.
Add the unsalted butter to the hot sweet potatoes. The heat will help melt the butter.
Use a potato masher, a fork, or an electric hand mixer to mash the sweet potatoes until they are smooth and free of lumps. If you prefer a chunkier texture, mash them to your desired consistency.
Gradually add the milk while continuing to mash the sweet potatoes. You can adjust the amount of milk to achieve your preferred level of creaminess.
Stir in the brown sugar, ground cinnamon, ground nutmeg, and a pinch of salt. Taste and adjust the sweetness and spices to your liking.
Transfer the mashed sweet potatoes to a serving dish.
Optionally, you can add a small pat of butter on top for extra richness.
Serve hot as a delightful side dish for your meal.