Over a high heat, bring a saucepan of water to the boil and add the potatoes. Boil for 15 to 20 minutes until tender.
Preheat the oven to 180 C / Gas 4.
Meanwhile, fry the beef over a medium heat for 5 to 10 minutes in a dry frying pan until evenly browned and drain off the liquid generated.
In a medium ovenproof dish, line the base with the sliced carrots. Layer the meat evenly on top of the carrots then sprinkle in the mixed herbs and pour over the stock.
Drain the boiled potatoes and add a splash of milk and the garlic butter then mash until well mixed and fluffy. Spoon the mixture evenly over the beef layer to cover.
Bake in the centre of the preheated oven for 25 minutes until piping hot. Remove from the oven and, if desired, place under the grill for a few minutes to brown the mash. Remove from the grill and serve.