Finnish Blueberry Pie (Mustikkapiirakka)

Preheat the oven to 175°C. Grease a 24–25 cm pie pan with 10 g softened butter.

Cream 140 g softened butter with 125 g sugar until light and fluffy. Beat in 1 egg and mix until smooth.

In a separate bowl, combine the wheat flour, baking powder, and salt. Add the dry mixture to the butter mixture and quickly work into a soft dough. Press it into the bottom of the pan, forming a low rim around the edge.

Scatter the blueberries evenly over the dough; if using frozen berries, there's no need to thaw them first.

For the topping, whisk together the sour cream, 70 g sugar, and 1 egg. Carefully pour the mixture over the blueberries, being careful not to damage the rim.

Bake the pie on the lower rack of the oven for 35–40 minutes, until the edges are golden brown and the center of the topping has set but still jiggles slightly when the pan is gently shaken.

Let the pie cool in the pan for at least 30 minutes before slicing. Serve warm or fully chilled.