1-Start your mushroom and lamb shank pot pies journey by preheating the oven to 160˚C (140˚C fan-forced), which sets the stage for tender results. Coat the 4 large Frenched lamb shanks in the ¼ cup plain flour mixed with salt and pepper, then shake off any excess for a light, even cover. Brown these shanks in 1 tablespoon of the olive oil over medium-high heat until they develop a flavorful crust, then set them aside to rest.

2-Next, in the same pan, heat the remaining 1 tablespoon olive oil and add the finely chopped brown onion, 3 crushed garlic cloves, 2 finely chopped celery sticks, 2 diced medium carrots, 300g quartered small button or Swiss Brown mushrooms, and 1 tablespoon finely chopped fresh rosemary leaves. Cook this mixture for 3-4 minutes until it softens and releases its aromas. Stir in the 2 tablespoons tomato paste and cook for another minute to deepen the flavors.

3-Pour in the 2 cups beef stock and 400g canned diced tomatoes, bring everything to a boil, then return the lamb shanks to the pan. Cover and bake for 2 to 2 ½ hours until the lamb is tender and the sauce has thickened nicely. Once done, remove the lamb, chop the meat, and mix it back with the mushroom mixture for a cohesive filling.

4-Divide the filling into 4 greased ovenproof dishes, each holding about 1½ cups or 10cm wide, to prepare for the final steps. Increase the oven temperature to 190˚C fan-forced and defrost the 2 sheets frozen butter puff pastry. Cut the pastry into 4 rounds, each 11cm in diameter, slightly larger than the dish edges for a good seal.

5-Top each dish with a pastry round, use a fork to seal the edges tightly, brush with the lightly beaten egg for a glossy finish, and cut a small cross in the center to let steam escape. Bake on a lined tray for 25-30 minutes until the pastry turns golden and puffs up perfectly. The total preparation time is about 35 minutes, with cooking and baking taking around 3 hours 15 minutes, making it a worthwhile effort for a comforting meal.