Preheat oven to 175c. Thinly slice potatoes- ideally with a mandolin

Bring equal parts cream and milk to a simmer in the pan - enough to cover the potatoes

Place potatoes slices in pan one at a time to ensure they don't stick together and cook for 4 minutes

Remove from heat. Spoon in a thin layer of cream on the base of ovenproof dish. Remove potatoes using slotted spoon and layer in the dish. Cover potatoes with remaining cream

Top with gruyere cheese and Place in oven at 175c for 30 mins