This rich gratin is a Swedish favourite. This is likely everyones temptation as Jansson is a common Swedish name.
50g / 2oz / 1/4 cup butter
900g / 2lb potatoes
2 large, sweet onions, sliced
2 x 50g / 2oz cans anchovies in olive oil drained
450ml / 3/4 pint / scant cups whipping cream or half and half double (heavy) and single (light) cream
a little milk (optional)
salt and ground black pepper
Preheat the oven to 200C / 400F / Gas 6. Use 15g / 1/2oz / 1 tbsp of the butter to grease a shallow 1.5 litre / 2 1/2 pint / 6 1/4 cup earthenware baking dish.
Using a small sharp knife, carefully cut the potatoes into thin slices, then cut the slices into fine matchstick strips.
Toss the potato strips with salt and ground black pepper and sprinkle half of them into the base of the prepared ovenproof dish.
Lay half of the onions on top of the potatoes, season with black pepper and dot with butter. Lay the anchovies on top of the onions, then add th erest of the sliced onions and top with the remaining potatoes. Mix the cream with 30ml / 2 tbsp cold water and pour this mixture over the potatoes and onions in the dish. Add a little milk if necessary to bring the liquid to just below the top of the final layer of potato matchstick strips.
Dot the potatoes with the remaining butter, then cover the dish with foil and bake for 1 hour.
Reduce the oven temperature to 180C / 350F / Gas 4 and remove the foil from the top of the dish. Bake for a further 40 – 50 minutes, or until the potatoes are tender when tested with a knife and brown in colour.
More Gratin Recipes
Jamie Oliver – The Perfect Potato Gratin
BBC Good Food – Potato And Leek Gratin
The Kitchn – Potato, Squash and Goats Cheese Gratin