Preheat oven to 180°C/350°F (160°C fan).

Brown beef: Sprinkle beef with ¾ tsp salt and ½ tsp pepper. Heat oil in a large heavy based pot over high heat. Brown beef aggressively in 2 to 3 batches. Then remove beef into a big bowl.

Wipe down pot: Wipe pot clean of burnt bits, if needed.

Cook bacon: Cool pot, add bacon. Place pot back onto medium heat. Cook bacon until golden. Then remove into bowl with beef.

Cook mushrooms: Melt 30g/ 2tbsp butter in the pot. Cook mushrooms until golden with a pinch of salt and pepper. Remove into separate bowl.

Cook other vegetables: Add onion, garlic, carrot and celery then cook for 5 minutes until onion is soft and sweet.

Oven slow cook: Add beef, bacon, Guinness, water, stock, ¼ tsp salt and ¾ tsp pepper. Stir then bring to simmer. Cover with lid, then transfer to oven for 1 hour.

Add mushrooms, then continue cooking in the oven for a further 1 hour.

Stove reduce: Remove pot from oven. Remove lid, then simmer on low heat for 20 minutes to reduce sauce.

Sauce thickener (Beurre Manié): Mix together butter and flour until smooth.

Thicken sauce: Stir Beurre Manié into sauce. Leave on the stove for another 2 minutes.

Cool: Cover pot with lid, then let it cool completely, preferably overnight.

Shortcrust base: Make and blind bake Shortcrust Pastry using a 23cm/9” pie dish. Let it cool for at least 15 minutes.

Preheat oven: Turn oven up to 200°C/390°F (180°C fan).

Fill pie: Bring filling to room temp. Fill pie with filling.

Puff pastry lid: Brush lip of pie crust base with egg, then top with puff pastry sheet. Trim excess with scissors, press to adhere to edges.

Egg wash: Brush top with remaining whisked egg, then make a 2.5cm / 1" X incision in middle to allow steam to escape.

Bake: Bake 45 - 50 minutes until top is super golden. Rest 5 minutes before serving.