1. Preheat the oven to 400˚ F. Line a sheet pan with parchment paper.
2. Mix the blueberries, 1/2 cup of sugar, the flour, lemon zest, lemon juice and Cassis in a large bowl. Carefully ease one pie crust into a 9-inch pie plate, making sure not to stretch the dough or it will shrink as the pie bakes. With a sharp knife, cut the excess dough off at the edge of the pie plate. Spoon the blueberry mixture into the pie shell, scraping the bowl with a rubber spatula to be sure you include all the juices.
3. Brush the edge of the crust with the egg wash. Carefully lay the second crust on top, again easing — not stretching — it onto the pie. Cut the excess dough off at the edge of the pie plate. Press the edges together with a dinner fork or crimp with your fingers. Brush the top crust with the egg wash, cut three slits for steam to escape and sprinkle with sugar.
4. Place the pie on the prepared sheet pan and bake in the middle of the oven for 45 to 50 minutes, until the filling is very bubbly and the crust is nicely browned. Allow to cool and serve warm or at room temperature.

Perfect Pie Crusts

1. Cut the butter in 1/2-inch dice and return it to the refrigerator while you prepare the flour mixture. Place the flour, sugar and salt in the bowl of a food processor fitted with the steel blade and pulse a few times to mix. Add the butter and shortening and pulse 10 to 12 times, until the butter is the size of peas. With the machine running, pour the ice water down the feed tube and pulse the machine until the dough begins to form a ball. Dump the dough out on a floured board and turn it into a ball. Wrap it in plastic wrap and refrigerate for 30 minutes.
2. Cut the dough in half. Roll each piece out on a well-floured board into a 12- to 13-inch circle, rolling from the center to the edge, turning and flouring the dough to make sure it doesn’t stick to the board.