Janssons frestelse (Jansson's Temptation)

Method

1. Heat the oven to 200 °C. Peel the potatoes and cut them into sticks about 5 mm thick and 5–6 cm long, like thin fries. Do not rinse them: their starch is what thickens the cream. Halve the onions and slice them thinly.

   Add in this stepFloury or all-purpose potatoes 500 gYellow onion 1

   oven

2. Melt half the butter in a 22 cm frying pan over medium heat and cook the onions for 6 min, stirring often, until soft and translucent but not browned.

   Add in this stepButter 10 g

   medium heat

3. Grease a 20×15 cm baking dish with a little of the butter left in the pan. Spread a third of the potatoes over the bottom, then half the onions and half the sprat fillets. Repeat, and finish with a final layer of potatoes. Season with white pepper and skip the salt: the sprats and their brine are salty enough.

   Add in this stepSwedish-style spiced sprat fillets (ansjovis) 60 gWhite pepper to taste

4. Stir the cream and milk together and pour half evenly over the potatoes, then drizzle over the sprat brine. Scatter the breadcrumbs on top and dot with the remaining butter in small pieces. Bake in the oven on the middle shelf for 20 min.

   Add in this stepDouble (heavy) cream 75 mlWhole milk 35 mlBrine from the sprat tin 1 tbspFine dried breadcrumbs 2 tbspButter 10 g

   oven

5. Pour the rest of the cream mixture down the sides of the dish, so the crust stays crisp, and return it to the oven for another 25 min, until the top is deep golden, the cream is bubbling and a knife slides easily through the potatoes. If the top browns too fast, cover it loosely with foil.

   Add in this stepDouble (heavy) cream 75 mlWhole milk 35 ml

   oven

6. Let the gratin rest for 5 min so the cream thickens and settles, then serve hot.