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Sliced mustikkapiirakka on a wooden board showing juicy blueberry filling and a golden custard-topped crust.

Mustikkapiirakka: Classic Baked Finnish Blueberry Pie

A press-in buttery crust filled with sugared blueberries and topped with a sour cream custard that bakes until just set.
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Prep Time 20 minutes
Cook Time 50 minutes
Total Time 2 hours
Servings: 8 servings
Course: Dessert
Cuisine: Finnish
Calories: 378
Ingredients Method Notes

Ingredients
  

Crust
  • 250 g all-purpose flour
  • 2 tbsp granulated sugar
  • 1/4 tsp salt
  • 125 g cold butter cubed
  • 2 cold water to 3 tbsp
Filling
  • 500 g blueberries fresh or frozen
  • 3 tbsp granulated sugar
  • 1 tbsp potato starch or cornstarch
Topping
  • 200 g sour cream full-fat
  • 1 egg large
  • 2 tbsp granulated sugar
  • 1 tsp vanilla sugar or 1 tsp vanilla extract

Method
 

Make the Crust
  1. 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.
  2. 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.
  3. 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.
  4. Blind bake for 10 to 12 minutes until the edges just start to turn golden. Remove and lower the oven to 175C/350F.
Fill and Bake
  1. Toss the blueberries with sugar and potato starch in a bowl until coated. Spread evenly over the warm crust.
  2. Whisk the sour cream, egg, sugar, and vanilla sugar together until smooth. Pour slowly over the berries.
  3. Bake for 35 to 40 minutes, until the custard topping is set at the edges and only slightly wobbly in the center.
  4. 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.