In the bowl of a stand mixer, whisk together the flour and yeast. Heat the milk, sour cream, sugar and salt in a medium saucepan over medium heat. Stir occasionally until just warm, about 3 minutes. You do not want it to simmer or boil. Add the milk mixture to the flour mixer. Beat with the dough hook. Add in the egg and beat until the dough pulls away from the sides of the bowl.

Remove the dough from the mixer bowl with lightly floured hands. Place in a large oiled bowl to rise. Cover and let rise at room temperature for about 90 minutes or until the dough has doubled in size.

For the filling: Mix together the blueberries, brown sugar and 4 tablespoons of the melted butter in a medium bowl.

For the glaze: Combine all ingredients in a food processor or blender and process until smooth. If you want an even smoother glaze you can strain it through a fine mesh sieve.

Assemble the rolls: Coat a 10 inch cast-iron skillet with vegetable oil or cooking spray. Once the dough has risen, place on a lightly floured work surface. Roll out the dough to a roughly 14×10 inch rectangle. Brush the dough with the extra 2 tablespoons of melted butter, all the way to the edges. Layer on the blueberry filling mixture evenly over the top.

Start to roll the dough from the long edge away from you. Seal the edge with some water or melted butter. Cut the log until you have about 10 1-inch tall slices.

Place the rolls in the prepared skillet snuggly, in a single layer. Bake for 30 minutes uncovered until the sweet rolls are golden brown. Remove from the oven and let cool before drizzling with the glaze. Top with fresh blueberries.