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There’s something about mustikkapiirakka, Finland’s blueberry pie, that feels like summer wrapped in a crust. Wild blueberries picked from the forest, folded into a short buttery base, and topped with a soft sour cream layer that bakes into something close to custard.
I first had this pie at a cabin outside Tampere, still warm from the oven. It wasn’t overly sweet. The tartness of the berries did most of the work.
This version uses a simple press-in pastry, no rolling pin drama, and a sour cream topping that sets in about 40 minutes. Frozen blueberries work fine here, so you can make it any month of the year.
If you’ve never baked with sour cream before, don’t worry. It behaves a lot like the baked cinnamon custard cups of jericalla and firms up as it cools.
Why You’ll Love This Recipe
- Press-in crust skips the rolling pin entirely
- Sour cream topping bakes into a soft custard
- Works with fresh or frozen blueberries year-round
- Tart berries balance the sweet custard layer
Ingredient Notes
- all-purpose flour: Regular flour keeps the crust tender. Don’t substitute bread flour, it turns the base tough.
- cold butter: Keep it cold and cubed so the crust stays short rather than dense.
- blueberries: Wild Finnish blueberries are smaller and tarter than cultivated ones. Frozen work well, just toss them straight from the freezer with the starch instead of thawing first.
- sour cream: Full-fat sour cream sets properly in the oven. Low-fat versions can turn watery.
- potato starch: Potato starch is traditional in Finnish baking and keeps the filling from turning soupy. Cornstarch works as a 1:1 swap.
- egg: One egg is enough to set the sour cream layer into a custard.
- vanilla sugar: Vanilla sugar is common in Finnish pantries. Swap in 1 tsp vanilla extract if you don’t have it.
Mustikkapiirakka: Classic Baked Finnish Blueberry Pie
Ingredients
Method
- Whisk the flour, sugar, and salt in a mixing bowl. Cut in the cold butter with your fingers until the mixture looks like coarse crumbs.
- Add cold water, 1 tbsp at a time, mixing just until the dough clumps together. Press into a disk, wrap, and chill for 30 minutes.
- Heat the oven to 200C/390F. Press the chilled dough evenly into a 23 cm / 9-inch tart pan, pushing it up the sides. Prick the base a few times with a fork.
- Blind bake for 10 to 12 minutes until the edges just start to turn golden. Remove and lower the oven to 175C/350F.
- Toss the blueberries with sugar and potato starch in a bowl until coated. Spread evenly over the warm crust.
- Whisk the sour cream, egg, sugar, and vanilla sugar together until smooth. Pour slowly over the berries.
- Bake for 35 to 40 minutes, until the custard topping is set at the edges and only slightly wobbly in the center.
- Cool on a wire rack for at least 20 minutes before slicing. Serve warm or chilled.
Notes
- Use a 23 cm / 9-inch tart pan with a removable bottom for easy slicing.
- Don't skip blind baking, the crust turns soggy under the wet filling otherwise.
- Frozen berries release more juice, add an extra teaspoon of starch if using them.
- The custard should wobble like set jelly, not slosh, when you shake the pan gently.
Tips for Success
- Chill the dough for a full 30 minutes so the butter stays firm when it hits the oven.
- Toss frozen blueberries straight from the freezer with starch so the filling doesn’t turn watery.
- Blind bake the crust for 10 to 12 minutes so it doesn’t turn soggy under the custard.
- Pour the sour cream topping over cooled berries, not hot ones, so it doesn’t curdle immediately.
- Let the pie cool for at least 20 minutes before slicing so the custard layer fully sets.
Variations
- Swap half the blueberries for lingonberries for a tarter, more traditional Finnish forest flavor.
- Add lemon zest to the sour cream topping for a brighter, slightly citrus finish.
- Use a rectangular sheet pan instead of a tart pan for a thinner, more rustic bake.
Storage and Reheating
Store mustikkapiirakka in the fridge, covered, for 3 to 4 days. The sour cream topping means it needs to stay chilled rather than sitting on the counter.
Warm a slice in the oven at 150C/300F for 8 to 10 minutes if you want it slightly warm, though it’s just as good cold straight from the fridge. Skip the microwave, it turns the custard layer rubbery.
The baked pie freezes for up to 2 months wrapped tightly, but like the layered custard in Venezuelan bienmesabe, the custard texture softens slightly after thawing. Thaw overnight in the fridge before serving.
Serving Suggestions
Serve mustikkapiirakka the way Finns do, in thin slices with a scoop of vanilla ice cream or a dollop of whipped cream.
A cup of black coffee cuts through the sweetness well. It’s the traditional pairing at Finnish summer cottages.
Leftover slices work for breakfast too, alongside plain yogurt and a handful of fresh berries.
FAQ
Why is my mustikkapiirakka custard topping runny in the middle?
The custard needs the full bake time to set, much like the dense custard and caramel in Venezuelan quesillo, usually 35 to 40 minutes at 175C/350F. If the center still jiggles like liquid rather than soft-set gelatin, give it another 5 minutes. It firms up more as it cools, so don’t judge it straight out of the oven.
Can I use crème fraîche instead of sour cream in mustikkapiirakka?
Yes, crème fraîche works as a 1:1 swap and sets just as well. It’s slightly richer and less tangy than sour cream, so the topping will taste milder. Full-fat Greek yogurt also works in a pinch, though the custard turns out a touch denser.
Can I make mustikkapiirakka a day ahead?
Yes, this pie actually tastes better the next day once the custard layer has fully set and chilled. Bake it, cool completely, then cover and refrigerate overnight. Slice cold or let it sit at room temperature for 20 minutes before serving.
What pairs well with mustikkapiirakka besides vanilla ice cream?
Whipped cream and black coffee are the classic Finnish pairing, especially at summer cottages. Cold milk works well too, especially for a breakfast-style slice. The tartness of the blueberries balances rich, plain toppings better than anything overly sweet and heavy.
Is mustikkapiirakka gluten free?
No, the traditional crust uses wheat flour, so it’s not gluten free as written. You can swap in a 1:1 gluten free flour blend for the pastry, though the crust will be more crumbly and less flaky. The custard topping itself is naturally gluten free.
What’s the difference between mustikkapiirakka and American blueberry pie?
Mustikkapiirakka has a short, press-in crust and a sour cream custard layer poured over the berries, while American blueberry pie usually has a double crust and no custard. The Finnish version is less sweet and leans on the berries’ tartness. It’s closer to a tart than a deep-dish pie.
Loved this? Try these next
- Classic Baked Venezuelan Quesillo with Caramel
- our Jericalla: Guadalajara’s Baked Cinnamon Custard Cups
- our Classic Zuppa Inglese with Vanilla-Chocolate Custard
- our Torta della Nonna: Baked Custard Tart with Pine Nuts
