Ryan Silber says he rarely cooks, but there he was at Hillel, the Jewish community center at UW-Madison, kneading a tub of flour and other ingredients. He?d had a hard week of tests and was ready to ?beat up on some dough,? he said. Silber, a freshman, is among a couple dozen students who spend every Thursday afternoon at Hillel baking 70 to 100 loaves of challah, the traditional Jewish egg bread….The UW-Madison students are part of a nationwide effort called ?Challah for Hunger,? with chapters at dozens of universities. In addition to raising money for charities, the effort keeps Jewish students connected to their cultural roots, both as bakers and customers.