Add some cooking oil (around 1 tbsp) to a large saucepan and heat. Once hot add in the onions and turn the heat down a touch. Fry until they begin to soften. Add the carrots. Stir. Cook for a further 2-3 minutes.

Add the lamb mince and brown off. Add the tomato paste, Worcester sauce and all the herbs and spices. Season well with salt and pepper. Stir everything together. Cook for 3-4 minutes.

Pour in the stock and bring to a simmer. Add a lid to the saucepan. Prepare the mash potatoes whilst the sauce simmers by adding in the butter and half the milk first, then using a masher, mash until a good consistency is achieved, season with salt and pepper then add the remaining milk plus 1tsp mint sauce and stir through until evenly distributed throughout. Set aside.

Once the gravy has reduced down and thickened nicely (this usually takes around 20 mins or so - if the sauce is too thick, simply add a dash of water in and stir through to loosen it up), add in the peas. Stir through. Cook for a further minute then remove from the heat.

Preheat your oven to 180 (fan) or gas mark 6. Add the lamb mixture into a oven proof dish then top with the mashed potatoes. Smooth over up to all the edges evenly. Bake for ten minutes then grill for a further five until the top is just golden and a little crisp.