Bring the milk to boil over medium heat. Remove from heat once boiling and add the butter to melt, then transfer to a bowl and let cool.

Add the egg and stir to combine.

In another bowl, combine flour, yeast, salt, and 3 tablespoons of the sugar. Add the milk mixture and mix until just combined. Then knead the dough, and form into a ball and cover with plastic wrap to sit for an hour or until it doubles.

On a lightly floured surface, toll the dough out to a 12 by 15 inch rectangle. Sprinkle the dough with the remaining sugar and sprinkle with the blueberries and cornstarch. Roll into a right coil, then cut into 12 equal pieces and put each in a cup from a muffin tin. Cover with plastic wrap and transfer to the fridge overnight.

About 3 hours before eating, take the tin out of the refrigerator. Let stand until doubled in size (2-2.5 hours), and preheat the oven to 350°F.

Bake for 20-24 minutes, and then serve warm sprinkled with powdered sugar.