Preheat your oven to 375°F (190°C). Roll out the chilled pie crust on a lightly floured surface into a circle about 12 inches in diameter.
Transfer the rolled crust into a 9-inch pie dish, gently pressing to fit and trimming excess edges.
In a mixing bowl, combine the pitted cherries, sugar, cornstarch, and lemon juice. Stir until the cherries are evenly coated and the mixture starts to thicken slightly.
Pour the cherry filling into the prepared pie crust, spreading it out evenly. Dot the filling with small pieces of butter for richness.
Cover the pie with the top crust or create a lattice pattern. Trim and crimp the edges to seal. Cut a few small vents in the top crust to allow steam to escape.
Brush the crust with the beaten egg to give it a shiny, golden appearance. Place the pie on a baking sheet to catch any drips and bake in the preheated oven for about 45 minutes, until the crust is golden brown and the filling is bubbling through the vents.
Remove the pie from the oven and let it cool for at least 2 hours to allow the filling to set. Slice and enjoy the warm, bubbling cherry pie with a flaky crust and a burst of sweet-tart flavor.
