Roll out one pie crust to be roughly 1/8" thick and line a pie dish with it. Trim any excess.
Wash and dry the blueberries and pour them into the pie dish. You want to see how many you need to fill your dish which is why the measurement is 4-5 cups.
Pour your berries to a large bowl and mix in the vanilla extract. Add the sugar, cornstarch, and cinnamon and stir to combine and thoroughly coat all of the berries.
Pour the berries back into the pie dish.
Roll out the second pie crust to also be approximately 1/8" thick. Using a pizza cutter, cut 3/4" wide strips and create a lattice pattern on top of the berries. Carefully trim any excess with a sharp knife.
Using a floured fork, gently crimp the ends of the crust.
Dice the butter in little pieces and place a piece in every opening of the lattice to ensure even distribution.
Bake the pie at 375 F for about 45 minutes. Keep an eye on it, and if the crust starts to brown too quickly, protect it with a pie shield or some tin foil until the lattice starts to brown and the pie is cooked.
Let cool for at least 4 hours.