In large bowl, toss plums, sugar, cinnamon, lemon juice, zest and 1 tablespoon flour until well combined. Spoon plum mixture over dough, leaving a 2 inch border around the edges. Sprinkle pistachios over the filling. Fold edge of dough over fruit filling, pleating together every few inches. Brush edges of dough with egg wash, and sprinkle with Wilton Sparkling Sugar. Bake 45-55 minutes or until crust is golden and fruit juices begin to bubble. Cool to room temperature on cooling grid.