The Bath bun is a rich, round yeast leaven sweet roll that has a lump of sugar baked in the bottom and more crushed sugar sprinkled on top after baking. Variations in ingredients include candied fruit peel, currants or larger raisins or sultanas.
It has been claimed that William Oliver, inventor of the Bath Oliver dry biscuit, also invented the Bath bun, but that it proved too fattening for his rheumatic patients. It is more likely that the Bath bun is descended from the 18th century 'Bath cake'. References to Bath buns date from 1763, and they are still produced in the Bath area of England. The original 18th century recipe used a brioche or rich egg and butter dough which was then covered with caraway seeds, coated in several layers of sugar similar to Frenchdragée.
The 18th century 'Bath cake' may have been the original of the Sally Lunn bun although this is disputed, but the Sally Lun bun also originates from Bath.