Place the chicken, oregano, ¼ cup fontina or gruyere or gouda cheese, ¼ cup cheddar, mayonnaise and ¼ cup sour cream in a bowl and mix well to combine. Spoon onto one half of each of the rolls and top with remaining halves. Heat a large non-stick frying pan over medium heat. Place the rolls in the pan and top with a plate and can to weigh down. Cook for 1?2 minutes on each side or until golden and the cheese is melted.