Place a piece of bread on a parchment lined tray. Cover the bread with mayo and cranberry sauce first, then dressing, then turkey and then the cheese on top.
Bake the open faced sandwich for about 7 - 8 mins or however long it takes for the cheese to melt and get all bubbly and brown.
Meanwhile, heat up the gravy if it needs it. Pull the sandwich out of the oven and pour the gravy on top.