Begin by cutting the beef chuck into approximately 1-inch chunks and seasoning them with salt and pepper.

Heat a large skillet or Dutch oven over medium-high heat. Brown the seasoned beef pieces for about 5 minutes on each side.

In the same skillet, add a splash of oil and sauté the onions, carrots, celery, and garlic for 5 to 7 minutes.

Pour in the Guinness stout and deglaze the skillet, allowing it to simmer for 2-3 minutes.

Return the browned beef, add beef stock, thyme, and bay leaves, and let it simmer gently for about 2 hours on low heat.

Mix flour with enough water to make a slurry, stir it into the filling, and cook for an additional 5 minutes.

Roll out your pie pastry and line half of it in the pie dish, then fill it with the beef mixture.

Roll out the second layer of pastry, place it on top, seal the edges, and make slits in the crust.

Preheat the oven to 400°F (200°C), bake the pie for 30 to 40 minutes until golden brown.