This is traditionally made with potatoes but can be made with any root vegetable or combination of root vegetables. Serves 4.450g potatoes1 shallot150ml double cream150ml whole milk2 tbsp grated gruyre25g butterNutmeg to grate1. Pre-heat the oven to 180C/gas mark4. 2. Use half the butter to grease one large or four individual ramekins or gratin dishes. Peel and finely chop the shallot and peel and very thinly slice the potatoes. 3. Layer the potatoes in the dishes with a small sprinkling of chopped shallot in between each. 4. Mix together the milk and double cream, a good grating of nutmeg and season to taste. 5. Pour over the potatoes, dot with the remaining butter and sprinkle over the gruyre.6. Cook for 45-50 minutes or until the potatoes are tender and the top is golden and bubbling.