Start by making your favorite double pie crust recipe. Once prepared, wrap the dough and chill as directed, dividing it into 2 disks.
For the filling, combine 1 cup of the blueberries with the sugar in a saucepan. Bring to a simmer over medium heat, stirring occasionally until the sugar melts, about 5 minutes.
In a small bowl, mix the cornstarch with the water. Whisk this mixture into the blueberry and sugar mixture in the saucepan.
Return the mixture to the heat, cooking and stirring constantly over low heat until it boils, thickens, and becomes clear, which should take around 5 to 7 minutes.
Pour this thickened mixture into a large bowl, then gently fold in the remaining blueberries, along with the lemon zest, cinnamon, and butter. Allow it to cool slightly.
Roll out one disk of the chilled pie crust and place it in the bottom of your pie plate. Trim the edges to fit.
Pour the cooled blueberry filling into the prepared crust, spreading it evenly.
Roll out the second disk to create the top crust. Cut it into 8-10 strips to make a lattice topping. You can weave the strips together or simply lay them in a crisscross pattern over the filling.
Seal and crimp the edges of the pie as desired, making sure it’s well sealed to hold in the filling.
Place the assembled pie, uncovered, in the freezer for 1 to 2 hours until the crust is firm enough to wrap. After this, wrap it well in plastic wrap, followed by heavy-duty foil. If you have large zip-lock bags, you can slide the pie into one and remove the air.
On the day you plan to bake the pie, take it out of the freezer and remove the wrappings. Set the pie on the counter while you preheat your oven.
Preheat the oven to 400ºF. Brush the top crust with cream and sprinkle with coarse sugar for extra sweetness.
Place the pie on a rimmed baking sheet to catch any drips, then immediately reduce the oven temperature to 375ºF.
Bake for one hour and 10 minutes or longer, until the crust is a golden color and the filling is bubbling up deliciously.
Finally, cool the pie on a rack before serving, allowing the filling to set beautifully.