In a medium sized pan that has a lid heat the olive oil over a medium heat. Add the diced onion and chopped garlic.
Sweat the onion and garlic for about 10 minutes with the lid on, stirring occasionally, until they are soft.
Add the herb stock pot and stir. Add the minced beef, breaking it up with a wooden spoon and combine with the onions and garlic.
When the mince starts to brown, stir in the Worcester sauce and cook for 1 minute.
Sprinkle the flour over the meat and mix in well and cook for a further minute.
Gradually add the rich beef stock, season with salt and pepper and bring to the boil. Reduce to a gentle simmer, place the lid on the pan and cook for 20 minutes, giving it a stir quite often so it doesn't stick.
Once the gravy has reduced by half and thickened, remove from the heat and allow to cool down.
Pre heat the oven to 200°C.
Put the mince mixture into a suitable pie dish, brush the edges of the dish with some of the beaten egg and lay the puff pastry over. Press the pastry firmly to the pie dish and trim the edges to remove the excess pastry.
Make a cross cut through the pastry in the centre to allow any steam out and glaze the pastry with the remaining beaten egg.
Put the pie on a baking tray and bake in the middle of the preheated oven for 20-25 minutes until the pastry is golden brown.