Pie Crust: If making 2 homemade pie crusts, prepare the dough and refrigerate for at least 45 minutes before rolling. If the dough has been refrigerated overnight, let it sit at room temperature until it's pliable enough to roll without cracking.
Preheat Oven to 400°
Start Filling: Add the 2 lbs fresh blueberries to a large bowl. Add the ¾ cup sugar, 1 tablespoon fresh lemon juice, 2 teaspoon lemon zest, 1 ½ teaspoon vanilla extract or bean paste , 2 tablespoon cornstarch, 3 tablespoon all purpose flour and ½ teaspoon kosher salt. Stir, tossing a good amount untl blueberries start releasing some natural juices and there is no visible dry ingredients.
Roll out Crust: Roll out your pie crusts and place first one into 9inch pie dish. When oven is preheated, add blueberries to pie dish inside crust. Spread blueberries evenly. Cover the top with your second crust and crimp edges. Be sure to cut two small slits in the center.
Bake: Beat egg & cream in a small dish and brush over crust before baking. Sprinkle with coarse sugar right before baking. Place in oven and bake 20 minutes. Lower temp to 375° & bake 35-45 more minutes. This pie can spill over so a baking sheet on the rack below to catch drippings is a good idea. If the crust is browning too quickly, add a pie shield or carefully tent with foil. Blueberries should be bubbling & crust will be golden brown. Remove from oven & let cool completely to set. It could take even longer depending on your oven.
Cool completely. Transfer the pie to a wire rack and allow it to cool completely before slicing so the blueberry filling has time to set. For the cleanest slices, give it at least 3 hours (you may need 4). Serve with vanilla ice cream.