Kneadinhttps://vimeo.com/125015071g a key into Challah the first Shabbos after Pesach:
Many are accustomed to braid the Challah in the shape of a key on the first Shabbos after Pesach. Others knead a key within the Challah dough on the first Shabbos after Pesach. Some acclaim the above custom is not followed by Chabad Chassidim.
The reason behind the custom:
On Pesach all the heavenly gates were open. After Pesach they are closed. The symbol of the key on the Challah is to show that we are opening the gates slightly through our honor of Shabbos, and Hashem will then open it fully for us. Alternatively it represents the opening of the gates of Parnasa, as after Pesach the Mun stopped falling and we were required to fend for our own livelihood. [Oheiv Yisrael of Rav Avraham Yehoshua Heshel of Apta]