Pre-heat oven to 180°c. Brush eight ½ cup capacity pie tins with oil. Use a 12cm round pastry cutter to cut 4 discs from each pastry sheet. Line the prepared tins with pastry. Place in the fridge for 15 minutes to rest.
Meanwhile, heat oil in a medium frying pan over medium heat. Cook the onion, stirring occasionally, for 3 minutes or until soft. Add the garlic and cook for a further minute. Add the mince and cook, stirring with a wooden spoon to break up any lumps, for 4 minutes or until the mince changes colour. Stir in stock, cook for 10 minutes or until reduced. Add Gravox Supreme Gravy Powder, chilli flakes and Worcestershire sauce. Cook for 5 minutes or until thickened slightly. Set aside to cool slightly.
Place potato in a large saucepan. Cover with cold water. Bring to the boil over medium-high heat. Cook for 20 minutes or until tender. Drain. Return to pan. Add the milk and butter. Mash until smooth. Season with salt and pepper
Divide the mince mixture among the pastry cases. Top with mash. Bake for 20 minutes or until golden.