Bring blueberries, sugar, citric acid to boil, stirring occasionally

Using 1/4 c cup measurement, mix 2 tbsp cornstarch and fill water, do this twice, then pour into blueberries, stir. It will thickened.

Cool blueberries to room temperature

Roll flat puff pastry (2 sheets) and make 4 (bigger) hand pies, with heaping 1/2 c of blueberries each, as the filling. Rerolled scraps. I managed to make 5 puff pastry/pie in the end.

Poke holes and brush with egg yolk

Bake for 30 mins, til golden brown, on preheated 375 F

Serve at room temperature or slightly warm out of the oven

Enjoy!