Prepare the Dough:

In a large mixing bowl, combine 2 1/4 cups of flour, sugar, yeast, and salt. Add the warm milk, melted butter, and egg. Beat until smooth. Gradually add the remaining flour until a soft dough forms.

Turn the dough onto a floured surface and knead for about 5 minutes, until smooth and elastic. Place the dough in a greased bowl, cover, and let rise in a warm place until doubled in size, about 1 hour.

Make the Filling:

In a small bowl, combine the blueberries, granulated sugar, brown sugar, cinnamon, and cornstarch. Mix until the blueberries are well coated.

Assemble the Rolls:

Punch down the dough and roll it out on a floured surface into a 15x9-inch rectangle. Spread the blueberry filling evenly over the dough.

Starting from a long side, roll the dough tightly into a log. Cut into 12 equal slices and place them in a greased baking dish.

Bake the Rolls:

Preheat your oven to 375°F (190°C). Cover the rolls and let them rise for 30 minutes. Bake for 25-30 minutes, or until golden brown. Allow the rolls to cool slightly.

Glaze:

In a small bowl, mix the powdered sugar, milk, and vanilla extract until smooth. Drizzle over the warm rolls.