Religious Committee
Here's the history of key-shaped challah on Shabbat after Passover
What is the meaning of the custom of braiding key-shaped challahs on the first Shabbat after Passover?
In 16th-century Prague, the shamash (beadle) of one of the synagogues was preparing to celebrate the Seder with his family...
As he began the Kidush, he heard a noise and noticed that the bunch of synagogue keys he had carefully hung up had fallen to the ground.
He picked them up and hung them back on the designated nail.
As he resumed the Seder, the keys fell again.
The phenomenon repeats itself and, stunned, he decides to go as quickly as possible to the Maharal [Rabbi Yehuda Levai ben Betzalel].
The Rav then advises him to hang them up one by one in order to discern if it is not one of them that is causing the problem and not the whole bunch…
He then runs back to his master to tell him that only the key of the Aron Kodesh is not staying in place.
The Rav then asks to go and check the thing more closely and to open the Holy Ark…
He then discovers with amazement inside a bottle filled with blood.
The Maharal asks to remain silent on this matter.
The verger, while having taken care to empty it of its contents filled it up with wine in its place, puts the bottle back in the same place.
The next day during Tefillah a monk accompanied by the police asks to search the synagogue because the Jewish community is accused of ritual murder.
He hurried to the Aron Kodesh and discovered a simple bottle filled with wine...
Following this event, the MAHARAL asked that this "miracle of the key" be remembered by making Halot in this form on the first Shabbat after Pesach, given the impossibility of making it with Matzot dough [even though the event took place on the very evening of the Seder].