Gently melt the butter and Castello Creamy Blue cheese together.
Generously grease the base of an ovenproof pan or baking dish with butter. Arrange the potato slices in the pan overlapping each other, brushing the melted butter and cheese mixutre over each layer and seasoning as you go.
Cover with greaseproof paper or a lid and bake in the oven for 45 minutes or up to 1 hour. Test with a skewer to see if the potatoes are cooked through. At this point you can serve the dish, or let it cool down and refrigerate to set to serve the next day. To serve the next day, turn the slice out of the pan and with a sharp knife cut it into desired portions. Warm portions in the oven a 160°C for 10-15 minutes.