• Heat a medium (26 cm/10-inch large) oven-friendly skillet with 2 tablespoons of olive oil over low heat. Add in the carrot, celery and onion and cook, stirring often for about 5 minutes, until the veggies have softened. Then tranfer the vegetables into a bowl until needed.
• Return the pot to medium heat, add in the lamb mince and cook, stirring often, until it's browned, pour in the wine and let it evaporate. Then scoop out with a spoon any excess fat.
• Add back in the veggies, then add the Worcestershire sauce, followed by the tomato paste, thyme and rosemary sprigs, and cook, stirring all the ingredients together, for a further 2 minutes.
• Pour the stock into the pot, bring to a gentle boil and simmer, covering the pot with a lid, for 20 minutes. Remove the lid and continue to cook for a further 10 minutes. Discard the thyme sprigs and season with sea salt and freshly-cracked black pepper to taste.
• Meanwhile, preheat the oven to 180 C/ fan 160 C/ gas 4.
• Remove the skillet from the heat, and top the meat with prepared mashed potatoes (see method below), then raffle the top with a fork. Alternatively, transfer the mashed potatoes into a piping bag and pipe on top of the meat.
• Transfer the skillet into the oven and bake for 10-15 minutes, then place under the grill for a further 5 minutes. Remove from the oven and allow the Shepherd's Pie to rest for 5 minutes before serving.

For the mashed potatoes:

• Place the potatoes in a large pot, cover with cold water and add 1 teaspoon of salt. Bring to a boil, uncover and simmer for about 20 minutes, or until the potatoes are tender and cooked through.
• Once the potatoes are ready, drain in a colander and peel whilst still hot. In the meantime, warm up your milk.
• Place the potatoes in a large bowl, add in softened butter and mash with the help of a potato masher.
• Slowly pour the warmed milk in, and continue to mash the potatoes until reaching the desired texture. Season with salt and pepper to taste and a pinch of nutmeg if you like.