Remove the potatoes from the oven and slice about 10 slits into each sweet potato, cutting only ¾ of the way through. Use dowels or wooden spoon handles on either side of your sweet potato to prevent slicing through fully.
Melt butter or coconut oil in a small heat safe bowl in the microwave. Add the cinnamon, nutmeg, and salt and mix together.
Gently fan the slices of the sweet potato out and then use a pastry brush to brush the glaze over the sweet potato getting in between each slice. Sprinkle with chopped nuts if using.
Return to the oven and bake for an additional 20-25 minutes, or until potatoes are fork tender. Serve immediately.
Preparing in Advance: You can get a jump start on this recipe by par-baking your sweet potatoes up to 3 days in advance. Refrigerate the sweet potatoes for up to 3 days and then when ready to serve, slice and glaze the sweet potatoes and bake at 400 degrees F for 25-30 minutes or until warmed through and fully tender. Leftovers: Store leftover baked sweet potatoes in the refrigerator for up to 3 days in an airtight container.