Preheat oven to 375°.
In a large bowl, combine cherries, sugar, cornstarch, lemon juice, and salt. Stir to combine; set aside.
On a lightly floured surface, roll out the larger piece of dough into an 18-by-12-inch rectangle.
Transfer to a 15-by-10-by-1-inch rimmed baking sheet, (pastry will hang over sides of pan).
Pour cherry mixture into lined baking sheet; set aside.
On a lightly floured surface, roll out remaining piece of dough into a 16-by-11-inch rectangle. Drape over filling.
Bring bottom pastry up and over top pastry. Pinch edges to seal. Using a fork, prick top crust all over. Brush with heavy cream or egg wash.
Bake until crust is golden and filling is bubbling, 40 to 55 minutes.
Transfer to a wire rack until just warm to the touch, about 45 minutes.
In a medium bowl, stir together confectioners’ sugar and milk, water or lemon juice (or combination thereof) until desired glaze consistency is achieved. Use a spoon to drizzle over top. Serve warm or room temperature.
