What is the source for group hafrashat challa events?

These events are relatively recent, so they don’t appear in early sources. We quote Rema OC 242:1, that it was customary for every woman to make sure she prepared enough dough to separate challa with a beracha in preparation for Shabbat and Yom Tov. (At these events, each woman should take home an amount of dough that would be obligated in separation, since splitting up dough into pieces can affect the halacha of separating challa.) Perhaps part of the impetus for challa evenings is that many women no longer bake much at home, so that these evenings might be a special opportunity to perform a mitzva associated with women. These events also take on their own power because of the spiritual group dynamic.

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