Fry the lamb mince on high heat until nicely browned (this will add to the flavour). Remove any fat with a spoon or dab with kitchen paper.

Add the smoked chipotle paste and plain flour. Stir well.

Stir in the onion, carrots, celery, garlic and rosemary. Reduce the heat and gently fry together for another 10 minutes.

Add the canned tomatoes, stock and seasoning. Bring to the boil and then simmer (with lid slightly ajar) for an hour (or longer if possible), stirring occasionally to prevent it from catching at the bottom.

Preheat the oven to 200°C (400°F, Gas 6).

Carefully top the lamb with the mashed potato, using a spatula. Add tiny knobs of butter all over the top of the potato.

Bake in the oven for 25 minutes or until golden on top (take care not to burn it). If you want the top crispy, pop it under a hot grill for a few minutes.