1. Make the Dough

1. Warm the milk until just lukewarm, about 100–105°F (38–40°C).
2. In a large mixing bowl or the bowl of a stand mixer, combine sifted flour, sugar, yeast, cardamom, and salt.
3. Add the lukewarm milk and egg. Mix with a dough hook attachment on low speed until a shaggy dough forms.
4. Begin adding the butter, one cube at a time, while kneading. Allow each piece to incorporate before adding the next.
5. Knead the dough on medium speed for about 8–10 minutes until soft, smooth, and elastic.
6. Shape the dough into a ball, place it in a lightly buttered bowl, cover with a towel or plastic wrap, and let rise in a warm spot until doubled in size—about 1 hour.

2. Cook the Blueberry Filling

1. While the dough is rising, place the blueberries, sugar, and lemon juice in a saucepan.
2. Cook over medium heat, stirring often, until the mixture thickens—about 15–20 minutes.
3. Let the filling cool to room temperature before using. It should be thick enough not to run out of the dough when rolled.

3. Roll and Shape the Buns

1. Once the dough has risen, turn it out onto a floured surface and gently punch it down.
2. Roll the dough into a large rectangle, about 20 x 15 inches (50 x 38 cm).
3. Spread the cooled blueberry mixture evenly over the surface, reaching to the edges.
4. Starting from the long edge, roll the dough into a tight log.
5. Cut the log into 12 even slices using a sharp knife or unflavored dental floss.
6. Place the slices cut-side up on a parchment-lined baking tray, leaving space between them.
7. Cover with a towel and let rise again for 40 minutes.

4. Bake and Finish

1. Preheat your oven to 400°F (200°C).
2. Once the buns have puffed up from the second rise, place them in the oven.
3. Bake for 10–12 minutes or until golden brown and cooked through.
4. While warm, brush each bun with melted butter and sprinkle with granulated sugar.
5. Transfer to a wire rack to cool slightly before serving.