Swedish Potato and Sprat Casserole with Cream
Janssons Frestelse is a beloved Swedish comfort casserole of thinly sliced potatoes layered with caramelized onions, umami-rich sprats (or bacon), and heavy cream, then baked until golden and bubbling. The dish balances creamy richness with salty, savory depth from preserved fish or bacon. Perfect for holiday dinners, special occasions, or whenever you want an impressive vegetable-forward side that serves a crowd. This version uses traditional Swedish sprats but welcomes bacon as an accessible substitute, making it adaptable to different pantries while maintaining its distinctive salty-savory character.
Ingredients
- 2 pound potatoes, peeled, sliced into 1/4 inch rounds then 1/4 inch strips
- 4 tablespoon butter, divided
- 2 yellow onions, thinly sliced, about 2 cups
- 1 can (3.5 ounce) sprats, Swedish preservedanchovy fillets1:1umamiseafoodadds fish
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- 3 cup heavy cream
- ½ cup bread crumbs
- salt, to taste
- ground white pepper, to taste
Instructions
- 1
Heat oven to 375F.
- 2
Slice potatoes into 1/4 inch rounds, then cut into 1/4 inch strips.
- 3
Heat butter in a saute pan over medium heat, add onions and saute until wilted and translucent, about 5 to 7 minutes.
- 4
Butter a deep casserole dish on bottom and sides.
- 5
Layer 1/3 of potatoes evenly over bottom, season lightly with salt and pepper.
- 6
Spread 1/2 of onions over potatoes, then half of sprats or bacon over onions.
- 7
Layer another third of potatoes, season lightly with salt and pepper.
- 8
Spread remaining onions over potatoes and rest of sprats or bacon.
- 9
Finish with remaining potatoes.
- 10
Bring cream to a simmer in a saucepan, then pour evenly into casserole.
- 11
Sprinkle breadcrumbs over top and dot with remaining butter.
- 12
Place casserole on baking sheet and bake until potatoes are cooked through and top is browned and bubbling, about 1 hour.
Tips
Slice potatoes uniformly so they cook evenly. A mandoline set to 1/4 inch makes this faster and more consistent.
Don't skip simmering the cream before pouring; it helps it distribute evenly and cook the potatoes more gently.
If sprats are unavailable or too strong, quality anchovy fillets work well, or use crispy bacon for a smokier take.
Good to Know
Cover and refrigerate up to 3 days. Reheat covered at 325F for 20-30 minutes until heated through.
Assemble casserole up to 8 hours ahead before baking. Store covered in refrigerator, then bake as directed (may add 10-15 minutes to baking time from cold).
Serve warm as a side dish alongside roasted meats, cured fish, or simple greens. Pairs well with aquavit or crisp white wine.
Common Mistakes
Slice potatoes thickly to avoid them breaking apart or staying undercooked.
Brown onions too much to prevent overpowering sweetness; keep them wilted and translucent.
Skip dotting butter on breadcrumbs to miss the golden, crispy topping.
Substitutions
FAQ
Can I make this without sprats or bacon?
Yes, though the dish loses its signature salty punch. Add extra salt and a spoonful of fish sauce or soy sauce to the cream, or use chopped anchovies for depth. The texture stays the same, but flavor becomes more delicate.
What if my potatoes stay crunchy after an hour?
Your oven may run cool. Cover the casserole loosely with foil and bake another 20-30 minutes. Slice a potato with a fork to test for tenderness. Very thick slices or starchy varieties may need extra time.
How long can I keep leftover casserole?
Refrigerated and covered, up to 3 days. Freeze up to 2 months; thaw overnight in the fridge and reheat covered at 325F for 30-40 minutes. Quality stays good but texture softens slightly after freezing.