Stir in the sweet potatoes, then stir in the brown sugar, granulated sugar, cinnamon, and nutmeg. Gently stir to combine. As the sugar melts into the butter, it will create a sauce. Once the sauce begins to simmer gently, cover the skillet.
6 large sweet potatoes, 1 cup granulated sugar, 1 cup brown sugar, 1 teaspoon cinnamon, 1/2 teaspoon nutmeg