Drain the pitted cherries and save 3 tablespoons of the juice.
In a small saucepan, combine the cherries and sugar. Heat over medium heat, bringing to a simmer until the sugar dissolves.
In a bowl, whisk together the cornstarch, lemon juice, and cherry juice, then add the cinnamon and almond extract. Stir this mixture into the cherries. Cook until the mixture thickens to a gel-like consistency. Remove from heat and let it cool completely.
Roll out one portion of the pie dough into a thin circle, slightly larger than your pie pan. Place it in the pie pan, leaving the edges overhanging.
Fill the crust with the cherry mixture.
Roll out the second piece of dough a bit thicker than the bottom one. Cut it into 6-8 strips, about 1 inch wide. Arrange these strips in a lattice pattern over the cherry filling.
Beat the egg with the water and brush it over the crust. You can sprinkle coarse sugar on top if you like.
Preheat the oven to 425F.
Bake the pie for 10 minutes, then reduce the heat and continue baking for another 50 minutes. In the last 10 minutes, cover the pie with aluminum foil to prevent over-browning.
Once done, let the pie cool completely before slicing and serving.