Combine ¼ cup of the sugar and the cornstarch very well in a small bowl. Set aside.
Add cherries, remaining ½ cup sugar and lemon juice to a saucepan or skillet. Cook over medium low until very juicy, about 10 minutes. Sprinkle sugar/cornstarch mixture over the cherries and stir well. Add salt.
Continue to simmer for 1 minute until the juices are completely thickened. Remove from heat. Add butter and almond extract (if using). Stir well and cool completely.
Fill unbaked pie shell with the cooled cherry filling. Whisk together the egg and water. Brush some of this egg wash onto the edge around the crust.
Top the pie with the second layer of pastry in a lattice pattern or a closed top. Trim any excess pastry and tuck the crust under itself. Create a fluted or any edge style you like. If you're using a traditional closed top, make little slits in the middle for steam vents. Chill pie in the freezer for 30 minutes.
Preheat oven to 425℉/218℃. Once the pie is well chilled, place on top of a parchment lined baking sheet. This will catch any leaking while the pie bakes. Brush entire crust with egg wash. Sprinkle with Turbinado or sanding sugar (if using). Bake at 425℉/218℃ for 20 minutes, then reduce temperature to 350℉/180℃ and bake another 45-50 minutes. The crust should be well golden and the cherries bubbling.
Cool pie for at least 3 hours before serving. Overnight is best. Enjoy with ice cream, whipped cream or nothing at all. Will keep on the counter for up to 2 days, refrigerated up to 5 days.