In a bowl, stir together your flour and salt. Using two butter knives, held against each other with one in each hand to form an “X,” cut your butter into your dough, with the knives pulling away from each other and back in, until you have a sand-like consistency.

Add your water (I like to put a few ice cubes in a glass before filling it with cold water to make sure it’s extra cold), stir together, and then compress the dough into two even balls. See the tip section if you have a food processor!

Place one of your dough balls between two large pieces of parchment paper, and roll to ⅛” thickness, making sure your dough is an even thickness throughout.

Gently peel the parchment back from the top layer, lay it back onto the dough, flip all of it over, and repeat with the bottom (now top) layer of parchment.

Removing one side of the parchment, carefully lay that side face down into a 9-inch pie dish and remove the top layer of parchment

Carefully shift the dough to ensure it is lying flat within the pan and along the sides. If you have more than an inch of excess, use a butter knife to cut away any extra and save it for later.

Tuck the remaining excess dough under along the edges to form your crust

Make a peace sign with your pointer and middle fingers on one hand, and place it along the edge of your crust. With the pointer finger of your other hand, pointing toward the center of the peace sign, pull back the dough in the center of your fingers. This will form a crimp. Repeat along the edge of your crust until complete.

Place your pie dish with the crimped crust in the fridge for 20 minutes

Roll out your other remaining dough ball – reusing your parchment paper – and place the flat sheet into the fridge to chill

Preheat your oven to 425°F

For your filling, in a bowl, stir together your sugar, flour, salt, and cinnamon. Add in your washed blueberries and combine

Remove your chilled pie crust from the fridge and pour the filling into the dish, spreading evenly. Dot your cubed butter across the top

With your remaining rolled crust, use a pastry wheel or pizza cutter to cut 6 strips. Lay 3 strips vertically across the top of your filling, about an inch apart. Then, one strip at a time, take one of your remaining strips and weave it over and under the vertical strips, horizontally. Repeat with the remaining strips, leaving an inch of space from one row to the next. If you start your weave under the first strip, for the next row, begin over that first strip

In a bowl, crack your egg and add in a splash of milk or water. Whisk together to form your egg wash

Brush your exposed crust with the egg wash and sprinkle with the coarse sugar

Place a baking tray on the rack below your pie to catch any blueberry drips

Bake on the middle rack for 20 minutes at 425°F, then, with the oven door shut, drop the temperature to 375°F and bake for an additional 40-45 minutes. The crust should be deeply golden, and the filling will be very bubbly. Keep an eye on your crust; if it starts to darken too early, loosely tent with foil to prevent the top from burning

Remove and allow to cool for at least 4 hours, preferably overnight. Slice and enjoy!