Preheat oven to 425°F (220°C).

Beat egg white until slightly foamy.

Rinse blueberries in a colander.

Gently roll blueberries in confectioners sugar to coat.

Empty pie crust mix into a large bowl.

Add butter and egg yolk to the pie crust mix.

Cut the butter and egg yolk into the pastry mix until it resembles coarse crumbs.

Sprinkle water, a tablespoon at a time, and mix until the dough just holds together.

Chill the dough for at least 10 minutes.

On a lightly floured board, roll the dough out to 1/8-inch thick.

Cut the dough into rectangle pieces of desired size for individual pies.

In a small bowl, mix together sugar and cinnamon.

Sprinkle the sugar and cinnamon mixture evenly over the dough rectangles.

Place a mound of the sugared blueberries on one half of each rectangle.

Fold the crust over the berries, creating a turnover shape.

Seal the 3 edges of each pie with a fork to prevent leakage.

Brush the top of each tart with beaten egg white for a golden finish.

Bake on an ungreased baking sheet for 15 minutes, or until golden brown.