01 - Set the oven temperature to 350°F (180°C).
02 - Heat 1 tablespoon of olive oil in a large heavy-based pan over medium-high heat. Brown the beef cubes in batches, transferring each browned batch to a plate.
03 - Add the remaining olive oil to the pan. Sauté onion, carrots, and celery for 5 minutes until softened.
04 - Stir in the minced garlic and cook for 1 minute. Add tomato paste and flour, cooking for 2 more minutes while stirring continuously.
05 - Gradually pour in beef stock, scraping browned bits from the pan. Stir in Worcestershire sauce, thyme, rosemary, bay leaves, then return the browned beef. Season with salt and pepper.
06 - Bring to a gentle simmer, cover, and cook for 1.5 hours, stirring occasionally, until beef is tender and gravy thickens. Remove bay leaves and allow filling to cool.
07 - Transfer the cooled beef mixture into a 1.5-quart (1.5-liter) pie dish.
08 - Roll out pastry to cover the dish. Place over filling, trim excess pastry, and crimp edges to seal. Cut a small steam vent in the center.
09 - Brush the pastry surface with beaten egg wash to promote golden browning.
10 - Bake for 30 to 35 minutes until the pastry is golden and crisp.
11 - Let the pie rest for 5 minutes to set before slicing and serving.