Friends brought this to a party once and I fell in love. It is wonderful.
Operating without a standard food processor requires cutting cold shortening into the dry ingredients by hand, utilizing a pastry blender to achieve pea-sized fat pockets that guarantee flaky layers. Incorporating ice-cold water gradually prevents the gluten from overdeveloping, which keeps the pastry tender rather than tough. Working the dough efficiently maintains the solid state of the fat before it enters the oven.
Replacing shortening with unsalted butter alters both flavor and texture. Butter contains water that evaporates during baking to create steam pockets, whereas shortening is one hundred percent fat and yields a more structurally stable crust that holds its crimped edges reliably. When substituting butter pound-for-pound, chill the dough thoroughly before rolling to compensate for butter's lower melting point.
Baking begins at a high temperature of 425 degrees Fahrenheit for 10 minutes to rapidly set the structural integrity of the pastry before reducing the heat to 350 degrees Fahrenheit for the remaining 30 to 40 minutes. This thermal shock prevents the bottom crust from becoming soggy as the blueberries release their natural juices into the sugar and flour thickener.