Mustikkapiirakka (Finnish Blueberry Pie)

Ingredients

• 150 g butter, melted and cooled
• 180 g white sugar
• 2 egg
• 2 tsp vanilla extract
• 220 g wheat flour
• 1½ tsp baking powder
• ½ tsp salt
• 400 g blueberry
• 1 tbsp cornstarch
• 250 g sour cream
• 1 tsp ground cinnamon

Method

1. 1.

   Mix the butter base — Heat the oven to 200°C and line the base of a 24 cm square tin with baking paper. Whisk the melted butter with 100 g of the sugar until glossy, then beat in one egg and 1 tsp of the vanilla extract.

2. 2.

   Press the dough into the tin — Fold in the flour, baking powder and salt to a soft, sticky dough. Press it evenly over the base of the tin and 2 cm up the sides with floured fingers — it should be about 5 mm thick, thicker at the corners than you think you need.

3. 3.

   Coat the berries in starch — Toss the blueberries with the cornstarch until every berry is dulled with a thin coat, then scatter them over the base in a single even layer. The starch is what stops their juice flooding the custard.

4. 4.

   Pour over the sour cream custard — Whisk the sour cream with the remaining 80 g sugar, the second egg, the remaining 1 tsp vanilla extract and the cinnamon until completely smooth. Pour it over the berries and tilt the tin so it runs into every corner.

5. 5.

   Bake until just set — Bake for 30-35 minutes, until the crust is deep golden at the rim and the custard is set with only a faint wobble in the middle. Purple juice will have bled up through the topping in places — that is exactly right.

6. 6.

   Cool before slicing — Cool completely in the tin, at least an hour — cut it warm and the custard runs. Slice into squares and serve at room temperature, on its own or with cold cream.