Fry the ground lamb in the oil over moderate to high heat for 2-3 minutes or until it slightly browned and season with salt and pepper.
Add in the onions and carrot into the ground lamb then grate the garlic in as well.
Add Worcestershire sauce, tomato paste, red wine, rosemary, and thyme to the pan, stirring constantly. Let the mixture simmer and reduce until the liquid has almost completely evaporated, which should take around 2-3 minutes.
Add chicken stock. After adding the chicken stock, bring the mixture to a boil and then reduce the heat to a simmer. Allow the sauce to thicken, stirring occasionally. Season with salt and pepper to taste.
While the sauce is simmering, cook the potatoes in boiling salted water until tender.
Drain potatoes and return to the hot pan
Mash the cooked potatoes until smooth with the milk, and butter and then add salt, pepper to taste. Add half of the grated Parmesan cheese and continue to mash until fully combined.
Spoon the lamb mixture into the bottom of an ovenproof dish.
Using a large spoon, layer the mashed potato on top of the lamb mixture
Top with remaining parmesan and season.
Fluff up the mashed potato and cheese with a fork to make rough peaks.
Bake in the oven for approximately 20 minutes, until bubbling and golden brown
