Boil sweet potatoes until fork-tender, 30-45 minutes depending upon their size. Drain and set aside to cool to the touch.
Preheat oven to 450 degrees F and spray a 2-quart baking dish. Peel potatoes and cut into 1/2” slices. Place potato slices in one layer in the dish, overlapping slices.
Melt butter in a small saucepan then add sugar and salt. Whisk until ingredients are incorporated and smooth. Pour evenly over the potatoes. Bake at 450F, 25-30 minutes or until are glazed and still shiny.