With the Passover prefiguring the Messianic redemption, and the matzah serving as its central symbol, the turning of the key into a matzah-looking challah as a reassurance that, as Ron puts it ...

On the last day of Passover, our focus shifts from the past redemption of the Jewish people from slavery in Egypt to the future redemption and the utopian Messianic era. While we eagerly await ...