For the buns, in a small saucepan, heat the milk over low heat until lukewarm.

In a stand mixer fitted with the dough hook attachment, combine the flour, sugar, yeast, cardamom, and salt. Add the lukewarm milk and egg. Knead on low for 8 minutes. Add the butter and knead on medium for about 5 minutes more, or until the dough is very elastic and somewhat moist. Transfer the dough to lightly buttered bowl, cover with a tea towel, and let rise in a warm spot for about 1 hour, or until doubled in size.

For the filling, in a medium saucepan, cook the wild blueberries, sugar, and lemon juice over medium-high heat, stirring often, for about 15 to 20 minutes or until thickened. Set aside to cool.

Once the dough has doubled in size, line a baking sheet with parchment paper.

On a lightly floured surface, using a rolling pin and more flour as needed to prevent sticking, roll out the dough into a large rectangle that measures roughly 20 x 15 inches (50 x 38 cm). Spread the filling evenly across the dough all the way to the edges. Starting on one of the long sides, roll the dough around the filling to form a long, roughly 20 inch (50 cm), log. Using a sharp knife, cut the log crosswise into 12 equal size buns. Place the buns on the prepared baking sheet, cover with a tea towel, and let rise in a warm spot for 40 minutes.

Preheat the oven to 400ºF (200ºC).

Bake for 10 to 12 minutes, or until nicely browned. While still warm, brush the tops with the melted butter then dip in granulated sugar to cover.

These buns are best eaten while they are still fresh, on the day they were baked.

Store at room temperature in an airtight container for up to 2 days.