Croque Monsieur and potato cakes

There's an old tea rooms in York called Betty's and they serve the most amazing croque monsieur so I tried a recipe out of one of the many cookbooks I own in the hope I could recreate that taste. You need lots of Gruyère cheese for this but my god it's amazing, a taste sensation! I served them up with some potato cakes which are quite fiddly to cook but do taste nice. Sorry about the quality of the photo, was taken on my phone.