1.Preheat oven to 200°C *180°C fan forced). Grease eight 9cm x 11.5cm (3¾-inch x 4¾-inch) oval pie tins.
2.Using an upturned pie tin as a guide, cut out eight ovals from puff pastry sheets. Refrigerate until needed.
3.Cut each sheet of shortcrust pastry into quarters to make eight squares. Roll squares out on a lightly floured surface until large enough to line each tin. Ease pastry into tins, press into bases and sides; trim edges. Prick bases with a fork. Line pastry with baking paper; fill with dried beans or rice. Place tins on oven trays. Bake 10 minutes. Remove beans and paper; bake further 5 minutes or until dry.
4.Heat half the oil in a large saucepan over high heat, cook mushrooms, stirring, for 8 minutes or until well browned. Remove from pan.
5.Heat remaining oil over medium-high heat in same pan, cook onion, stirring, until soft. Add beef, cook, stirring, over high heat until browned.
6.Blend cornflour and ¼ cup of the stock in a small bowl until smooth, stir in tomato paste. Return mushrooms to pan with cornflour mixture, remaining stock and pepper. Bring to the boil. Reduce heat, simmer, 3 minutes or until thickened. Cool.
7.Fill pastry cases with beef mixture. Brush edges of pastry with a little egg. Place puff pastry ovals on pies, press edges to seal. Brush tops with a little more egg. Cut a small slit in top of pies to allow steam to escape.
8.Bake pies for 30 minutes or until pastry is golden.
Pies will keep refrigerated in an airtight container for up to 2 days. They can be frozen uncooked or cooked. Uncooked pies can be baked from frozen. Thaw pies before re-heating.Note