Drain any excess liquid. In a large bowl, mash roasted potatoes with melted butter, milk, brown sugar, eggs, vanilla, cinnamon, and salt until smooth and creamy.
3 lb sweet potatoes, 0.5 cup unsalted butter, 0.5 cup milk, 0.333 cup packed brown sugar, 2 large eggs, 1 tsp vanilla extract, 0.5 tsp ground cinnamon, 0.25 tsp salt