Savor the brief cherry-growing season with this tart that is a symphony of sweetness.
Preheat oven to 400 degrees. Toss cherries, granulated sugar, cornstarch, and salt in a bowl; set aside. Whisk egg and cream in a small bowl; set egg wash aside.
Turn out dough onto a lightly floured work surface. Roll into a 16-inch round, about 1/8 inch thick. Transfer to a large baking sheet lined with parchment paper. Spread cherry mixture over dough, leaving a 2-inch border around edge. Fold dough over edges of filling. Brush dough with egg wash; sprinkle with sanding sugar. Refrigerate 15 minutes.
Bake tart until edges are dark golden brown and cherries are bubbling and cooked through, about 1 hour. Let cool on sheet on a wire rack 15 minutes. Transfer tart to rack to cool completely.
If you can't find fresh cherries, substitute thawed frozen ones.