Sweetened Potato Casserole (Imelletty Perunalaatikko)

Sweetened Potato Casserole, or Imelletty Perunalaatikko, is a traditional Finnish Christmas dish made by naturally sweetening mashed starchy potatoes with flour before baking. Soft and lightly sweet, it is served alongside Christmas ham or turkey and salads, making it a comforting and authentic addition to any holiday table. Adding a bit of dark syrup is optional, as the natural sweetening process already creates a mildly sweet, rich flavor.

Finnish Sweetened Potato Casserole Is a Family Tradition

This casserole has been part of my family’s Christmas celebrations for as long as I can remember. My mom adored nutmeg, and when I was a child, it was mandatory to grate a whole nutmeg directly into the potato mixture. The warm, spicy aroma of fresh nutmeg mixed with butter and potatoes is one of my fondest Christmas memories. Today, stores in Finland mostly carry powdered nutmeg, which works just as well, though the flavor is slightly milder and different.

I like to add a small amount of dark syrup to enhance the sweetness, but it is optional. The magic of imelletty, the natural sweetening process where flour reacts with warm mashed potatoes, ensures the casserole develops a gentle, caramel-like sweetness on its own. This slow process gives the casserole its unique flavor and creamy texture, unlike any other potato dish.

Tips for the Perfect Sweetened Potato Casserole

• Use starchy potatoes.
• Choose a large baking dish because the casserole bubbles in the oven.
• Freshly grated nutmeg adds a lovely aroma, but powdered nutmeg works too.
• Dark syrup is optional, taste the mixture and add syrup if you prefer a slightly sweeter casserole.
• Let the flour sit on hot mashed potatoes to achieve natural sweetness.
• Prepare ahead: You can freeze the mixture before baking. Freezing at this stage ensures the casserole maintains the perfect creamy texture when baked.
• Baking sweetens it further: The casserole develops more sweetness while baking, so don’t worry if it seems mild before it goes in the oven.

This casserole is a beloved family recipe, rooted in years of tradition. The combination of nutmeg, butter, and naturally sweetened potatoes creates a distinctive flavor that defines Imelletty Perunalaatikko. Whether you’re preparing it for the first time or following a family tradition, this classic Finnish dish is sure to be a highlight at the table.

Explore More Finnish Christmas Recipes

• Carrot Casserole (Porkkanalaatikko)
• Rutabaga Casserole (Lanttulaatikko)
• Cured Salmon
• Rosolli Salad
• Mushroom Salad

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Sweetened Finnish Potato Casserole (Imelletty Perunalaatikko)

Sweetened Finnish Potato Casserole — Imelletty Perunalaatikko — is a classic Christmas dish where mashed potatoes are naturally sweetened with flour before baking into a soft, creamy, and lightly sweet casserole. It’s one of Finland’s traditional holiday vegetable bakes, typically served alongside Christmas ham, gravies, salads, and other casseroles. This comforting dish develops a rich, mellow flavor as it cooks and tastes even better when reheated the next day.

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Prep Time 1 hour hr

Cook Time 3 hours hrs

Sweetening time 4 hours hrs

Total Time 8 hours hrs

Course Side Dish

Cuisine Finnish

Servings 10 people

Ingredients

  

• 2.5 kg starchy potatoes (about 5.5 lbs)
• Water for boiling
• 100-150 g butter (7–10 tbsp)
• 3-5 tbsp all-purpose flour
• 6-8 dl milk (2.5–3.5 cups) adjust as needed for desired consistency
• 3 tsp salt
• 1 tsp nutmeg freshly grated or powdered
• 2-4 tbsp dark syrup optional

Instructions

 

• Wash the potatoes and boil them with the skins on until fully cooked.
• Peel them while they are still very hot.
• Mash the potatoes immediately and mix in a few knobs of butter. Spread the mash into a large bowl and smooth the surface lightly.
• Sprinkle enough flour on top to lightly cover the surface. Let the mash sweeten at warm room temperature for about 2 hours.
• Stir the mash, smooth the top again, and sprinkle another thin layer of flour. Let it continue to sweeten for another 2 hours.
• Heat the milk until just boiling. Add the milk to the potato mixture gradually, stirring well. Add the milk gradually to reach a loose, porridge-like consistency.
• Mix in 2 tbsp butter, nutmeg, and salt. Taste, the mixture should be mildly sweet and rich. Add the syrup if using.

If preparing ahead

• At this stage, you can portion the mixture into freezer containers and freeze it for later use.

Bake the Casserole

• Thaw the mixture first if frozen. Transfer it into one large or two smaller baking dishes. (Use a large enough dish — this casserole bubbles in the oven.)
• Smooth the surface and create a pattern with a fork. Dot with a few small pieces of butter.

Baking times

• Bake at 125°C (257°F) for 1 hour, then reduce the temperature to 100°C (212°F) and bake for an additional 2 hours.
• The casserole will thicken and sweeten as it bakes.

Notes

This casserole bubbles in the oven, so choose a generously sized baking dish.

You can reheat it the next day — it firms up as it cools, but the flavor remains excellent.

The natural sweetness comes from the flour reacting with the warm mashed potatoes, so avoid letting the potatoes cool before adding the flour.

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