In a large bowl, toss the sweet potatoes with the melted butter, granulated sugar, brown sugar, cinnamon, nutmeg, and salt.
1/2 cup 1 stick unsalted butter, 1 cup granulated sugar, 1/2 cup maple syrup, 1 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg, 1/4 teaspoon salt