Preheat your oven to 200°C/180°C/Gas 6. Fill and boil your kettle. Finely chop the rosemary leaves, tip them into a roasting tin and set to one side.

Trim the roots and top 3cm off the leek. Halve it, rinse out any grit and finely slice it. Finely shred half the cabbage, discarding any really thick bits of core (see our tip on what to do with your extra cabbage half). Set the leek and cabbage aside.

Peel and roughly chop the potatoes. Tip them into a large pan and cover them with hot water from the kettle. Add a good pinch of salt, pop on a lid and bring to the boil. When the water is boiling, turn the heat down and simmer for 15 mins till the potatoes are soft when pierced with a knife.

While the potatoes simmer, pour 1 tbsp olive oil into a large frying pan on a high heat and warm it for 3-4 mins. Rub the lamb chops with a pinch of salt and pepper. When the pan is smoking hot, add the lamb and brown for 2 mins on each side.

Transfer the lamb to the roasting tin and turn to coat it in the rosemary. Slide the tin into the oven and roast for 10 mins, then lift the lamb chops out of the tin and set aside on a warm plate or board, loosely covered with foil, to rest for 5 mins.

While the lamb roasts, put the frying pan back on a medium-low heat. Add half the butter to the pan and melt it. Add the leek and cabbage with a pinch of salt. Cook for 6-8 mins, stirring often, till the veg is softened and bright green.

Drain the potatoes if you haven't already and tip them back in the pan. Using a potato masher, crush the potatoes till smooth, then mash in the remaining butter and trickle in 100ml of the milk. Add a good crack of black pepper and some salt. Stir in the cooked leek and cabbage.

Serve the rosemary lamb chops with the colcannon mash, drizzled with any resting juices.