Janssons Frestelse

Janssons Frestelse (Jansson's Temptation)

A classic Swedish Christmas casserole of layered matchstick potatoes, sweet onions, and salty cured sprats baked under a blanket of cream until golden and bubbling. Traditionally served with beer, aquavit, and a spoonful of cold lingonberry jam.

Prep

25 min

Cook

50 min

Total

75 min

Serves

6

Difficulty

Easy

Recipe ingredients

• •800 g (1 lb 12 oz) starchy potatoes, e.g. Bintje, King Edward, or russet; peeled
• •2 whole (2 medium) yellow onions, thinly sliced into half-moons
• •125 g (4½ oz) canned Swedish ansjovis (sprats), the small, heavily salted fermented/soured sprats sold in Sweden as 'ansjovis'; do not substitute Italian anchovies packed in oil without adjusting salt and rinsing first
• •40 g (½ cup) butter, plus extra for greasing
• •300 ml (1¼ cups) heavy cream, whipping cream, around 35% fat
• •125 ml (½ cup) milk
• •30 g (¼ cup) dry breadcrumbs, Swedish-style coarse breadcrumbs if available
• •1 tbsp freshly grated nutmeg, lightly grated; a few scrapes on a microplane
• •2 whole bay leaves, optional, but traditional in many recipes
• •1 pinch white pepper, go light; the fish is already salty
• •1 tbsp butter, melted, for the top

Steps

1. 1 Preheat the oven to 200°C (400°F). Generously butter a shallow 2-litre (about 8-cup) baking dish.
2. 2 Slice the peeled potatoes into thin matchsticks, roughly 4 mm (⅛-inch) thick. (Julienne on a mandoline or cut by hand into neat strips; do not use grated potato, which will turn to mush.)
3. 3 Melt 20 g (about 1½ tbsp) of the butter in a small skillet over medium heat and soften the sliced onions with a pinch of white pepper for 4–5 minutes until translucent but not browned. Set aside.
4. 4 Open the can of ansjovis and drain off the brine (or, for the very salty Swedish tinned sprats, give a quick rinse and pat dry). Cut the fillets in half crosswise so they distribute evenly.
5. 5 Toss the potato matchsticks in a bowl with the remaining 20 g (about 1½ tbsp) butter, melted, and the grated nutmeg so every stick is lightly coated.
6. 6 Layer one third of the potatoes in the buttered dish, top with half the onions and half the sprats. Repeat with another third of the potatoes, the remaining onions, and the remaining sprats. Finish with the last third of the potatoes, arranging them neatly.
7. 7 Tuck the bay leaves into the top layer if using.
8. 8 Pour the cream and milk evenly over the potatoes. Press down gently so the liquid rises up around the potatoes; the top should be just submerged. If it looks dry, add another 50 ml (¼ cup) cream.
9. 9 Cover the dish tightly with foil and bake on the middle rack for 30 minutes.
10. 10 Remove the foil, scatter the breadcrumbs evenly over the surface, drizzle with the melted butter, and return to the oven uncovered for 15–20 minutes until the top is deeply golden brown and the potatoes are completely tender when pierced with a skewer (no resistance in the centre).
11. 11 Bake until the cream is bubbling vigorously at the edges and the breadcrumbs are toasted a deep hazelnut colour. If the top browns before the centre is cooked, tent loosely with foil and continue. Internal temperature in the centre of the potatoes should reach at least 90°C (195°F).
12. 12 Let the casserole rest for 10 minutes so the cream sets to a creamy (not soupy) consistency. Serve hot, straight from the dish, with cold beer or aquavit, a small bowl of lingonberry jam on the side, and a simple green salad. Taste before adding any salt — the sprats make this dish naturally quite salty.