If you like the luscious convenience of a Gratin Dauphinoise, then you will be seduced by this version, which is made in a flash. It goes well with most meat dishes and is the ultimate in comfort food on a cold day, but equally good on a hot one. Prepare in advance and cover with foil. Slip into the oven the next day, removing the foil beforehand.
2-3 fat garlic cloves
2 sprigs of rosemary
500g sweet potatoes, peeled and shaped to fit down the feeder tube
350g large white potatoes (eg. Maris Piper or King Edwards) peeled and shaped to fit down the feeder tube
600ml double cream
200g Gruyérè or Emmenthal cheese, rind removed
salt and pepper
You will need a large, shallow ovenproof dish, well buttered
Heat the oven to 175ºC/Gas Mark 3-4
Using the small bowl fitted with its chopping blade, chop the garlic, and scatter some over the base of the dish.
Pull the leaves off the rosemary stalk and set aside.
Use the large bowl with the adjustable slicing disc at its thickest setting to slice the potatoes.
Lay the slices neatly over each other, starting with the white potatoes and seasoning as you go with salt, pepper, garlic and rosemary. Cover with a thick layer of sweet potatoes, then white, and continue until the dish is full to within 4cm of the top.
Pour the cream over the potatoes.
Using the medium bowl fitted with the shredding disc (large holes), grate the cheese. Sprinkle evenly over the potatoes and dot with the butter.
Place in the centre of the oven. The Gratin should cook perfectly in one hour. If guests are late getting to the table, cover with foil, turn down the oven, and it will keep beautifully.
If you can, allow it to stand in a warm place for 10 minutes, which will allow the cream to set and to cut more neatly into portions. If you are serving with a grill or roast with no sauce, serve immediately, so the thick, garlicky cream oozes onto the plates.