Peel and boil the sweet potatoes until just fork tender - about 15 minutes. Remove from heat and immediately drain really well.
Transfer potatoes to a large frypan or electric skillet. Add the remaining ingredients, brown sugar, butter & syrup. Turn heat to medium until the butter and brown sugar melts and the mixture is thick and bubbly. Reduce heat to low and simmer for about 1 1/2 hours, basting every 10-15 minutes.