In a bowl, whisk milk, eggs, butter and salt together.
In the bowl of a stand mixer, whisk together the flour, yeast, and sugar.
With the mixer on low, slowly add the wet ingredients to the dry ingredients.
Mix on low until all ingredients are combined.
Turn up speed to medium and knead for 8-10 minutes, or until the dough is not sticking to the sides.
Transfer the dough to a greased bowl, cover and let dough rise for 1-1½ hours or until double in size.
Line two baking sheets with parchment paper.
Divide dough into 16 evenly sized pieces and form them into balls.
Place balls on the lined pans and cover. Let rise 90 minutes.
Meanwhile, make the filling by cooking all ingredients in a small saucepan over medium-low heat until thickened. Set aside.
Preheat oven to 350℉.
Grease and flour the bottom of a measuring cup or glass that is about 2-2½ inches in diameter.
Press down in the centre of each dough ball to form an indentation that almost reaches the bottom but not all the way through.
Fill each dough ball with blueberry filling, using about 1½ to 2 tablespoons of filling.
Bake in preheated oven for 20-23 minutes. Do not overbake. The pastries should be light in colour. If they start turning golden, remove them immediately.
Let cool for 20 minutes. Dust with powdered sugar and serve.