Preheat the oven to 400 degrees F. Line a pizza stone or baking sheet with parchment paper.
Toss together the confectioners' sugar, cornstarch, almond extract, peaches and plums in a bowl.
Unroll the pie crust on the prepared pizza stone or baking sheet and spread the jam in the center. Top with the fruit mixture, leaving a 1 1/2-inch border. Fold the edge of the dough over the filling. Beat the egg in a small bowl with 1 teaspoon water. Brush the dough with the egg wash and sprinkle with the turbinado sugar.
Bake until the crust is golden brown and shiny, 35 to 40 minutes. Let cool for 15 minutes before serving. Serve with vanilla ice cream or whipped cream and dust with confectioners' sugar.