Pre-heat oven to 200°C/392 F.
Remove the pastry from the freezer to partially thaw while the pie filling cools.
Then, use your pie tins as a guide to cut the shortcrust pastry about 2.5cm/1" wider (all the way around) than the pie tins. Be generous, the excess pastry can be trimmed away later.
Cut the puff pastry lids to the size of your pie tins, to fit over the top with a little overlap.
Gently press the shortcrust pastry bases into your pie tins and use a fork to press holes in the bottom. Trim any long edges away, so that the pastry reaches the edges at the top of the tin.
Cover the pastry bases with a sheet of baking paper and cover with baking beads, uncooked beans or lentils (to help the pastry hold its shape as it bakes).
Blind bake for around 10 minutes, until the pastry is firm but still pale. Remove from the oven and place the bases on a wire rack (leave them in the tins). Remove the baking paper and baking beads, ready to assemble the pies.
Increase the oven temperature to 220°C/428 F.
Spoon the cooled pie filling into the pastry bases, about ½ cup of filling per pie.
Top the pies with the puff pastry lids, trim any excess pastry from the sides and use a fork to seal the edges to the base.
Brush the pastry tops with egg wash (optional).
Bake for a further 20 minutes, or until the pastry is crisp and golden and the filling is steaming hot in the middle. *As the pie filling is already cooked when assembling the pies, you only need to bake until the pastry is crisp and golden and the pies are hot all the way through.
Serve immediately with your favourite salad, chips or veggies.