Although hot cross buns are now available throughout Easter, they were traditionally eaten on Good Friday. People used to hang them in their house on Good Friday to protect them from bad spirits and believed that they would stay fresh until next Good Friday.
Queen Elizabeth I banned the sale of hot cross buns except on Good Friday, funerals and the day before Christmas as they were too special to eat any other day. To get around the ban the public started baking them at home but if they were caught they had to give the buns up to the poor.
Even before Medieval times, bakers marked crosses on their products as they believed it wold ward off evil spirits who would make the bread go bad. In the 1600's marking baked goods with a cross was condemned by the puritans in much of the UK except for certain goods on certain occasions, such as Good Friday. This is when hot cross buns became a 'special' bread and is what sets them apart for everyday buns.