Preheat the oven to 400°F (200°C). Lightly grease a 9x13-inch baking dish.

Place the cubed sweet potatoes in a large pot and cover with cold water. Add a pinch of salt and bring to a boil. Cook until just tender when pierced with a fork, 8 to 10 minutes. Drain well.

While the potatoes cook, make the glaze. In a small saucepan over medium heat, melt the butter. Stir in the brown sugar until it dissolves. Add maple syrup (or honey), vanilla, cinnamon, nutmeg, and salt. Cook for 1 to 2 minutes until slightly thickened. If it seems too thick, add 1 to 2 tablespoons water or orange juice to loosen.

Arrange the drained sweet potatoes in the prepared baking dish. Pour the glaze evenly over the potatoes and gently toss to coat the pieces.

Bake uncovered for 20 minutes. Carefully remove from the oven and sprinkle the mini marshmallows evenly over the top. If using nuts, scatter them on now.

Return the dish to the oven and bake for another 5 to 8 minutes, or until the marshmallows are puffed and golden. For an extra toasty top, place the dish under the broiler for 30 to 60 seconds, watching closely so the marshmallows do not burn.

Let the dish rest for 5 minutes before serving. The glaze will thicken a bit as it cools. Serve warm.