2 tablespoons unsalted butter, cut into small pieces
For the Crust:
All-purpose flour, for surface
1 large egg, lightly beaten with 2 tablespoons heavy cream, for egg wash
For the Pate Brisee: Pulse flour and salt in a food processor to combine. Add butter; pulse until mixture resembles coarse crumbs with some larger pieces remaining. Evenly drizzle 1/4 cup ice water over mixture. Pulse until dough is crumbly but holds together when squeezed. If dough is too dry, add up to 1/4 cup more ice water, 1 tablespoon at a time, and pulse to combine.
Turn out dough onto a floured surface and divide dough in half, then shape each half into a disk. Wrap each half in plastic and refrigerate until firm, about 1 hour or up to 1 day. (Dough can be frozen up to 1 month; thaw overnight in refrigerator before using.)
Make the filling: Preheat oven to 375 degrees. Toss together the cherries, sugar, cornstarch, and vanilla in a bowl.
Make the crust: Roll out 1 disk pate brisee to a 1/8-inch thickness on a lightly floured surface. Fit dough into a 9-inch pie plate. Pour in filling; dot with butter. Refrigerate while making top crust.
Roll remaining disk pate brisee to a 1/8-inch thickness on a lightly floured surface. Cut out 4 to 5 holes using a 3/4-inch round cookie cutter or pastry tip. Place on top of pie.
Trim bottom and top crusts to a 1-inch overhang using kitchen shears and press together to seal around edges. Fold edges under; crimp as desired. Freeze for 20 minutes.
Brush crust with egg wash. Bake pie on a foil-lined rimmed baking sheet set on the middle rack, until pie is bubbling in center and crust is golden, 1 1/2 to 1 3/4 hours. Transfer pie to a wire rack and let cool before serving.