Mustikkapiiras (Blueberry Yogurt Pie)

Across Finland in late summer, foraged wild blueberries (mustikat) end up in this exact pie at every grandmother’s kitchen table. This blueberry yogurt version uses a press-in butter cookie crust and a tangy yogurt-and-lemon custard that wraps around fresh berries during the bake.

The crust is unusual for a pie. Butter, sugar, an egg, flour, and baking powder beat together into a soft dough that gets pressed straight into the pan with floured fingertips, no rolling required. It bakes up like a thick shortbread, sturdy enough to support a wet custard filling without going soggy.

The filling is where the Finnish identity comes through. Plain yogurt, two eggs, sugar, fresh lemon juice, and vanilla whisk smooth into a barely-sweet custard that lets the blueberries lead. The yogurt’s tang is the signature.

Pour the custard over berries scattered in the crust and bake until set and golden. Chill thoroughly before slicing. The pie tastes brighter the next day, after the lemon and yogurt have time to bloom.

Pro Tips

• Use full-fat plain yogurt, not Greek or low-fat. Greek is too thick and makes the custard heavy; low-fat lacks the richness needed for a tender custard.
• Toss the blueberries in 1 teaspoon of flour before adding to the shell. This helps suspend them in the custard instead of letting them sink to the bottom.
• Don’t skip the chill. The custard sets as it cools and the flavors integrate. Warm slices are loose and soupy.
• If using frozen blueberries, do not thaw. They release excess water as they thaw and turn the custard runny.

Variations

• Swap blueberries for lingonberries for a more authentically Nordic, slightly tart version.
• Use a mix of blueberries and raspberries for a brighter, mixed-berry filling.
• Stir 1 tablespoon of grated lemon zest into the custard for an even more pronounced citrus note.