Sour Cherry Pie
3 pints pitted sour cherries, halved,1 cup (or more if you’d like it sweeter) granulated sugar, plus more for the top,4 to 5 tablespoons cornstarch (use 5 if you like a thicker filling),One recipe easy pie dough, one half shaped and chilled in a pie plate, the other rolled out flat and chilled on a floured sheet pan