Burnt bacon mound is the result of accidentally burning a raw bacon mound while attempting to make a bacon mound. Cooking a bacon heap requires 54 Cooking, and burning it will become less common with a higher Cooking level. It appears that the burnability of bacon in general is based on the lowest-level raw bacon, which requires only 14 Cooking. Players stop burning raw bacon mounds at 49 cooking, but cooking the mound requires 54; hence this item is unobtainable.
The burnt bacon mound has no use whatsoever. Unlike most burnt food, it is not tradeable.