Wash the sweet potatoes well and pierce the skin several times with a fork. Place the sweet potatoes on a rimmed baking sheet lined with foil and bake at 400 for 45-60 minutes, until tender. Note: actual baking time depends on the side of the sweet potatoes and may vary.
Very carefully peel the skin off the hot sweet potatoes and place the orange flesh of the potatoes into a large mixing bowl; discard the skin.
Add the melted butter and salt; whip the sweet potatoes with an electric mixer until smooth and creamy in texture.
Stir in the brown sugar.
Notes
Garnish with items of your choice: pats of butter, freshly ground black pepper, brown sugar, or ground cinnamon.