Place potatoes in a large pot and cover with about 1 inch of water. Season generously with salt. Bring the mixture to a simmer over medium-high heat. Reduce the heat to low and simmer, uncovered, until the potatoes are very tender, about 15-20 minutes. Drain well.
Add butter, milk and brown sugar to the hot potatoes; mash with a potato masher or, for a fluffier, smoother texture, beat on high speed with an electric mixer. Season with salt and pepper, to taste.
Notes
How to mash sweet potatoes by hand: You can mash sweet potatoes using a potato masher or large fork, which will give the dish a nice, rustic consistency. If you prefer smoother, fluffier mashed sweet potatoes, use a hand mixer, immersion blender or food processor.
Spices for Mashed Sweet Potatoes: If you would like some warm spices in your mashed sweet potatoes, you can add 1/2 teaspoon ground cinnamon, 1/4 teaspoon ground ginger, and 1/8 teaspoon ground nutmeg. If you prefer more savory seasonings, try adding herbs such as parsley, thyme, chives or rosemary.
To serve a larger family, double all of the ingredients. The rest of the cooking instructions remain the same.
I prefer 2% or whole milk in this mashed sweet potatoes recipe, because the higher fat content yields a smoother, creamier dish. You can substitute with half-and-half or heavy cream, if you like.
Make sure that the milk and butter is at room-temp or warm. Adding cold ingredients to hot potatoes brings down the temperature of the dish (lukewarm potatoes do not taste as good!), and it also makes it harder for the potatoes to absorb the liquid. If your potatoes can absorb more liquid, they will turn out creamier!