The second Monday in the New Year or Monday after 'Driekoningen' (the visit of the 3 Kings to the baby Jesus on January 6th) is traditionally the day for us people in Antwerp to eat "worstenbrood" or "appelbollen' (translated into sausagebread and appelpiebread) ..
Even when I worked for my former boss, the firm used to ask their people what they preffered and we all got our piece of sweetness for lunch (or at 4 o'clock to eat with our afternoon tea or coffee...).
Other sources refer back to the Antwerp port. Traditionally, the port workers got free drinks on the Monday after the first Sunday after Epiphany at the expense of the nation bosses. On top of that, something warm to eat was offered to them, consisting of meat and bread.