Heat oven to 450°F. In large bowl, mix pluots, 3/4 cup sugar, the tapioca, cinnamon and nutmeg. Let stand 15 minutes.
Meanwhile, make pie crusts as directed on box for Two-Crust Pie using 9-inch tart pan with removable bottom. Brush egg white over crust. Pour pluot mixture into crust-lined pan. Top with second crust and flute; cut slits in several places. Brush top with egg white; sprinkle with 2 tablespoons sugar.
Bake 25 to 35 minutes or until golden brown. Cover with sheet of foil during last 10 minutes of baking to prevent excessive browning. Cool at least 2 hours before serving.