Put the milk in a large heavy saucepan then season and add the butter. Bring to a boil.
Add the polenta slowly in a thin steady stream, stirring constantly. Reduce the heat to low and cooking, stirring occasionally , for 30 minutes. If you are using quick cook polenta follow the instructions on the packet.
Add the cheeses, blend well and cook for about 5 minutes until the cheeses have melted. SErve immediately.