To prepare pie crust, add the flour, sugar and salt to a stand mixer with paddle attachment or whisk attachment. Beat on low to combine. Add cold butter, beat until most of the butter is the size of small peas with the flour mixture.
With the mixer on, slowly add the ice water until dough forms and is combined.
Transfer dough to a lightly floured countertop, kneading a couple times to combine. Divide dough in half, flatten slightly and wrap tightly with plastic wrap. Refrigerate for 2-3 hours or freeze for 30 minutes before using. When ready to use, roll out round large enough to fit your pie plate. Transfer to pie dish and crimp the edges as desired.
To prepare blueberry pie filling, place blueberries, corn starch, sugar and lemon juice into a large saucepan over medium heat. Stir and let mixture cook, boil and bubble until thickened, about 7-10 minutes. Remove from heat and let cool for 15 minutes before transferring to pie crust.
Preheat oven to 375 degrees F. Pour pie filling into bottom pie crust spreading evenly. Top with second pie crust. Form a lattice topping or just a full pie crust with slits on top. Mix egg and water together then brush top of pie with egg wash and sprinkle with sugar. Bake for 50-55 minutes, until crust is golden brown. Remove and let cool for 15-20 minutes before serving. Serve with scoops of vanilla ice cream on top if desired.