Preheat the oven to 375°F.
In a large saucepan set over medium heat, cook the cherries and sugar, stirring occasionally, for 5 minutes.
3 pounds cherries, ¾ cup granulated sugar
In a small bowl, stir together the cornstarch, lemon juice, and salt until smooth. Fold into warm cherries. Cook 2-3 minutes, stirring frequently, until mixture is very thick. Remove from heat.
¼ cup cornstarch, 2 tablespoons lemon juice, ¼ teaspoon kosher salt
Press 1 pie crust into the bottom and up the sides of a 9-inch pie pan. Pour the cherry mixture into the prepared crust.
2 refrigerated 9-inch pie crusts
Unroll the remaining piecrust onto a lightly floured surface. Using a pastry wheel or knife, cut into 1-inch-wide strips. Weave strips in a lattice onto the cherry mixture. Trim the pastry strips even with the pie pan, and press the edges of the crusts together. Fold the edges under and crimp as desired. Brush the lattice with the heavy cream.
2 tablespoons heavy cream
Bake for 20-25 minutes, until the filling is hot and bubbly and the crust is browned. Let cool for at least 1 hour before serving.