Butternut and Potato Dauphinoise

I must have peeled and sliced over 10 000 potatoes during my time as entremetier (vegetable chef) at the brasserie – the menu had every potato dish imaginable, from silky mash and crisp roast potatoes to hand-cut chips and pommes boulangère, but my favourite was always the creamy potato Dauphinoise. I still make this dish, but have given it my own touch by adding some sweet butternut.