Preheat the oven to 375℉.
Wash and peel the sweet potatoes. Cut them into 1 inch thick slices and place them in a 9x13 baking dish, single layer (will cook evenly). Set aside.
In a saucepan add butter, molasses, sugar, and spices. Let boil and simmer until thickened. Mix well.
Remove from the heat and add in the vanilla extract. Mix.
Pour or drizzle about ¾ of the spiced sugar syrup glaze over the sweet potatoes. Set aside the remaining glaze.
Cover the baking dish with foil. Place into the oven.
Bake covered for 40-45 minutes. Carefully remove cover to check doneness, fork tender.
Raise the oven temperature to broil or 475℉.
Spread the remaining spiced sugar glaze onto the sweet potatoes and return the dish to the oven.
Cook for an additional 5-7 minutes until its brown and bubbly. Remove from the oven and allow it to cool. Enjoy.