Unroll puff pastry sheets, leaving pastry on parchment paper. Lightly flour and roll each sheet to 11-inch (28 cm) square. Cut each sheet into 4 equal squares. Cut corners off pastry to make rough rounds. Using parchment paper, transfer pastry to large baking sheet.
Peel peaches and cut into thin wedges; place in large bowl with berries. Sprinkle with lemon juice and gently mix.
In small bowl, combine granulated sugar, fl our and nutmeg; sprinkle over fruit and toss gently.
Divide fruit mixture evenly into centre of each circle, leaving 1-1/2-inch (4 cm) border. Fold edge of the dough up and over filling, pinching pastry to enclose filling. Brush edges with egg and sprinkle with coarse sugar.
Bake in 375 F (190 C) oven for 20 to 25 minutes or until pastry is golden brown and peaches are tender. Place tarts on wire rack to cool. Serve warm or at room temperature, lightly dusted with icing sugar.