4 pounds sweet potatoes (about 5 medium), peeled
1/2 cup unsweetened pineapple juice
4 tablespoons unsalted butter
1 cup packed light brown sugar
1 teaspoon ground cinnamon
1/4 teaspoon ground nutmeg
1/2 teaspoon kosher salt
Cut the potatoes in half crosswise. Cut each half into quarters.
Place the potatoes in a large saucepan and cover with cold water. Bring to a boil over medium heat, then simmer, reducing the heat as needed, until the potatoes are barely fork-tender, 3 to 5 minutes. Drain the potatoes and set aside.
Meanwhile, combine the pineapple juice, butter, sugar, cinnamon, nutmeg, and salt in a wide, high-sided skillet over medium-high heat. Stir continuously to dissolve the sugar. Bring to a boil, then add the potatoes. Cook, stirring occasionally, until the liquid is reduced and thickened to form a glaze over the potatoes, 10 to 12 minutes. Serve immediately.