When Rochel Schulgasser asks her neighbor Nava to bring over a house key each spring, it isn’t because Nava needs daffodils watered or a repairman let in. It’s always right after Passover, so it’s not like Nava has gone out of town and needs someone to housesit her home in Passaic, New Jersey. Instead, Schulgasser asks for her neighbor’s key so that she can bake it inside a challah bread. You know, as one does. Each year, on the first Sabbath after Passover, Schulgasser bakes shlissel challahs for her family…