Swedish Janssons Frestelse: Creamy Potato and Anchovy Casserole

Name: Swedish Janssons Frestelse: Creamy Potato and Anchovy Casserole
Prep time: 25 min
Cook time: 1 h 15 min
Total time: 1 h 50 min
Yield: 6 side-dish servings
Cuisine: International
Ingredients: 1 kg peeled floury potatoes: Russet or King Edward potatoes work well; weigh after peeling.; 300 g yellow onions: Peeled, halved, and thinly sliced.; 25 g unsalted butter: Divided into 10 g for greasing the dish and 15 g for cooking the onions.; 80 g drained Swedish ansjovis fillets: Reserve 30 ml of their brine before draining, then cut the fillets into small pieces.; 400 ml heavy cream: Approximately 35–36% fat.; 120 ml whole milk.; 30 ml reserved ansjovis brine: This seasons the potatoes and contributes the characteristic gently spiced flavor.; 1/4 teaspoon freshly ground black pepper.; 40 g plain, fine, dry breadcrumbs.; 20 g cold unsalted butter: Cut into small cubes.

Imperial November 8, 2026November 8, 2026

Quick Recipe Version (TL;DR)

Swedish Janssons Frestelse is a comforting Christmas casserole of slender potato strips, sweet onions, gently seasoned fish, and cream, finished with a crisp, buttery breadcrumb topping. For the traditional flavor, use Swedish ansjovis: spice-cured sprats, not ordinary salt-cured anchovies.

Yield: 6 side-dish servings
Prep Time: 25 minutes
Cook Time: 1 hour 15 minutes
Rest Time: 10 minutes
Total Time: 1 hour 50 minutes

Quick Ingredients

1 kg peeled floury potatoes, such as Russet or King Edward
300 g yellow onions, thinly sliced
45 g unsalted butter, divided: 10 g for the dish, 15 g for the onions, and 20 g for the topping
80 g drained Swedish ansjovis fillets, plus 30 ml reserved brine
400 ml heavy cream, approximately 35–36% fat
120 ml whole milk
40 g plain, fine, dry breadcrumbs
1/4 teaspoon freshly ground black pepper

Do This

1. Heat the oven to 200°C / 400°F, or 180°C fan. Grease a 2.5-liter baking dish with 10 g butter.
2. Soften the onions in 15 g butter over medium-low heat for 10 minutes, stirring frequently.
3. Cut the potatoes into matchsticks approximately 3 mm thick and 5 cm long. Do not rinse after cutting.
4. Layer half the potatoes, all the onions and ansjovis, and the remaining potatoes. Mix the cream, milk, reserved brine, and pepper; pour over.
5. Sprinkle with breadcrumbs and dot with the remaining 20 g butter. Bake for 65 minutes, checking after 40 minutes and covering loosely with foil if needed.
6. Check that the potatoes are completely tender, then rest for 10 minutes before serving.

Why You’ll Love This Recipe

Creamy underneath, crisp on top: The potatoes absorb the cream while the buttery breadcrumbs turn golden and crunchy.
A gentle savory flavor: Swedish ansjovis melts into the filling, adding warmth and depth rather than an overpowering fish taste.
Perfect for a holiday table: This traditional Swedish Christmas favorite pairs beautifully with ham, meatballs, and a crisp green salad.
Simple ingredients, special results: There is no separate sauce to make, and the oven does most of the work.

Grocery List

Produce: Enough floury potatoes to yield 1 kg after peeling; 300 g yellow onions, about 2 medium.
Dairy: 45 g unsalted butter, 400 ml heavy cream, and 120 ml whole milk.
Pantry: Swedish ansjovis sufficient to provide 80 g drained fillets and 30 ml brine, 40 g plain dry breadcrumbs, and black pepper. Check refrigerated Scandinavian specialty sections for ansjovis.

Full Ingredients

For the Potato and Onion Layers

1 kg peeled floury potatoes: Russet or King Edward potatoes work well; weigh after peeling.
300 g yellow onions: Peeled, halved, and thinly sliced.
25 g unsalted butter: Divided into 10 g for greasing the dish and 15 g for cooking the onions.
80 g drained Swedish ansjovis fillets: Reserve 30 ml of their brine before draining, then cut the fillets into small pieces.

For the Cream Mixture

400 ml heavy cream: Approximately 35–36% fat.
120 ml whole milk.
30 ml reserved ansjovis brine: This seasons the potatoes and contributes the characteristic gently spiced flavor.
1/4 teaspoon freshly ground black pepper.

For the Crisp Topping

40 g plain, fine, dry breadcrumbs.
20 g cold unsalted butter: Cut into small cubes.

Important ingredient note: Swedish ansjovis are spice-cured sprats, usually sold in a sweetly spiced brine. They are different from the salty anchovies commonly packed in oil. A 125 g tin may provide approximately 80 g drained fish, but check the label because pack sizes vary. No additional salt is needed in this recipe.

If Swedish ansjovis is unavailable: Use 20 g drained oil-packed anchovy fillets, finely chopped, and replace the 30 ml brine with 30 ml additional whole milk. This makes a pleasant adaptation, although it will not have the traditional sweet-spiced flavor.

Swedish Janssons Frestelse: Creamy Potato and Anchovy Casserole – Closeup

Step-by-Step Instructions

Step 1: Heat the oven and prepare the dish

Heat the oven to 200°C / 400°F, or 180°C fan, with a rack in the middle. Grease the bottom and sides of a 2.5-liter baking dish, approximately 28 × 20 × 6 cm, with 10 g of the butter. Set the dish on a rimmed baking sheet to catch any bubbling cream.

Step 2: Gently soften the onions

Melt 15 g butter in a large skillet over medium-low heat. Add the sliced onions and cook for 10 minutes, stirring frequently, until softened and translucent. Aim for sweet, tender onions rather than deeply browned ones. Remove the skillet from the heat.

Step 3: Cut the potatoes and prepare the fish

Cut the peeled potatoes into thin slices, then into matchsticks approximately 3 mm thick and 5 cm long. Keep the thickness as even as possible so the potatoes cook at the same rate.

Do not rinse or soak the cut potatoes. Their surface starch helps thicken the cream into a sauce. Measure 30 ml brine from the ansjovis container, then drain and weigh 80 g of fillets. Cut the fish into small pieces for even distribution.

Step 4: Build the layers and add the cream

Spread half the potato matchsticks in the prepared dish. Scatter all the softened onions over them, followed by the ansjovis pieces. Finish with the remaining potatoes, distributing them evenly without packing them down tightly.

Stir together the heavy cream, milk, reserved brine, and black pepper. Pour slowly and evenly over the potatoes. The liquid should settle around the layers without completely covering the uppermost potato strips.

Step 5: Add the buttery breadcrumb topping

Sprinkle the breadcrumbs evenly over the surface, then dot with the remaining 20 g cold butter. Keep the topping loose rather than pressing it into the cream; this helps it develop a crisp, golden crust.

Step 6: Bake until golden and completely tender

Bake for 65 minutes total. Check after 40 minutes; if the breadcrumbs are already nicely golden, cover the dish loosely with foil for the remaining 25 minutes. Otherwise, leave it uncovered and watch the color toward the end.

The casserole is ready when the edges are bubbling, the top is golden brown, and a thin knife slides through the center potatoes without resistance. If the potatoes still feel firm, cover loosely and continue baking in 10-minute intervals until tender. The cream should be thickened but still moist underneath the crust.

Step 7: Rest and serve

Remove the casserole from the oven and let it rest for 10 minutes. This allows the cream to settle into the potatoes, making the casserole easier to serve while keeping the inside soft and luscious.

Spoon generous portions onto warm plates, keeping some crisp topping on each serving. Serve alongside Swedish meatballs, roast ham, or a sharp mustard-dressed salad. The traditional presentation needs no cheese or elaborate garnish.

Pro Tips

Choose the right fish: Look specifically for Swedish ansjovis or spice-cured sprats. Substituting the same weight of ordinary anchovies would make the casserole much saltier.
Keep the potato strips slender: Thick batons take longer to soften and can leave you with a browned top before the center is ready.
Save the starch: Skipping the rinse is important here; the potato starch gives the cream body without flour.
Protect the topping: A loose foil tent prevents overbrowning while allowing the potatoes to finish cooking.
Judge tenderness, not just color: A beautiful crust does not necessarily mean the potatoes underneath are done. Always test the center with a knife.

Variations

Gluten-free: Replace the breadcrumbs with 40 g fine, dry gluten-free breadcrumbs. Check the ansjovis label for any gluten-containing ingredients.
Slightly lighter: Use 300 ml heavy cream and 220 ml whole milk instead of the original cream and milk quantities. The result will be a little less rich, with a slightly looser sauce.
More pronounced ansjovis flavor: Increase the reserved brine to 45 ml and reduce the whole milk to 105 ml. Keep the amount of fish unchanged.

Storage & Make-Ahead

Refrigerate: Transfer leftovers to shallow, covered containers and refrigerate within 2 hours of baking. Keep for up to 3 days.

Make ahead: For the best texture and color, bake the casserole completely rather than storing it assembled with raw potatoes. Bake up to 1 day ahead, cool promptly, cover, and refrigerate. Reheat covered at 180°C / 350°F for approximately 45 minutes, then uncover for 10 minutes to refresh the crust. Check that the center reaches 74°C / 165°F; continue heating if necessary. Use a baking dish suitable for refrigerator-to-oven reheating.

Freeze: Freeze cooled portions in airtight containers for up to 2 months. Thaw overnight in the refrigerator before reheating. The potatoes and cream may be slightly softer after freezing.

Nutrition (per serving)

Estimated for one-sixth of the casserole, using Swedish ansjovis and the full-fat ingredients. Sodium varies considerably by fish brand and brine.