In a large bowl, combine warm milk, 2 tablespoons sugar, and yeast. Let stand for 5-10 minutes, or until foamy.
In a separate bowl, whisk together flour and salt.
Add the flour mixture to the yeast mixture, along with the melted butter and egg. Stir until a dough forms.
Turn the dough out onto a lightly floured surface and knead for 8-10 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, turning to coat.
Cover and let rise in a warm place for 1-2 hours, or until doubled in size.
Roll out the dough into a 12x15-inch rectangle on a lightly floured surface.
Spread softened butter evenly over the dough.
In a small bowl, combine sugar and cinnamon.
Sprinkle the sugar-cinnamon mixture evenly over the butter.
Top with blueberries.
Roll the dough up tightly, starting from one of the longer sides.
Cut the roll into 8-10 equal pieces.
Place the rolls in a greased baking dish.
Cover and let rise for 30-40 minutes, or until doubled in size.
Preheat oven to 350°F (175°C).
Bake for 20-25 minutes, or until golden brown.
Let the rolls cool slightly before serving.