Heat a pananni pan or use a cast iron skillet to very warm but not scorching hot.
Butter one side of each piece of sourdough or Tuscan bread. On other side of bread spread marinara on one and mozzarella on the other. Lay the anchovy fillets on one side. Sprinkle with oregano. Close the sandwich and place into the press. Or if using a skillet brown on one side, then flip and brown the other. If cheese needs more time take pan off heat and tent with foil for a minute or two.