Preheat the oven to 200 degrees C. Cut the potatoes into circles of medium thickness. Put the potatoes on parchment and grease with melted butter.
Bake in a preheated oven for 30 to 40 minutes or until slightly brown on both sides, turning once.
Fry the bacon and chop. When the potatoes are ready, put the bacon, cheese and green onions on top, put in the oven again until the cheese is melted.