Sweet potato shepherd's pie is one of those dishes that improves with a little interference. The classic version is fine — lamb, onion, mash, oven — but add a handful of warm spices, a glass of beer and a topping of sweet potato and carrot mash, and something rather more interesting happens.

The sweet potato topping of sweet potato shepherd's pie does the talking — spiced lamb underneath, golden crust on top.

If you have leftover lamb from a roast leg or shoulder, finely chop it rather than mincing — the texture is far better. The spice mix here is earthy and warming rather than hot; cumin, allspice, coriander, a whisper of turmeric and nutmeg, and a half-inch of cinnamon stick doing quiet work in the background.

For other ways to use up leftover lamb, my Leftover Lamb Shepherd's Pie takes the traditional route, and the Leftover Lamb Pie with Goat's Cheese wraps everything in filo for something altogether more theatrical.

A note on the mash

The mash is where this pie earns its character. Potato alone would be fine — potato with sweet potato and carrot is considerably better. The sweetness of the sweet potato plays against the spices in the meat beautifully, and the carrot adds a gentle earthiness. Don't skip it.

A note on the beer

In my casa, it would be Cruzcampo or Mahou — whatever's cold and open. A light lager works well; nothing too bitter or dark.

One tip worth keeping

If you want the mash to stay on top rather than sinking into the meat and juices, allow the lamb mixture to cool in the fridge before adding the potato. Since we haven't added stock and the alcohol will have virtually evaporated, it isn't strictly necessary here — but it's a good habit for any shepherd's pie.

Sweet and Spicy Shepherd's Pie

Serves 2, amply

Ingredients

• 250g leftover lamb leg or shoulder, finely chopped
• 200g potatoes, peeled and quartered
• 1 sweet potato, peeled and cut into large chunks
• 1 carrot, peeled and sliced
• 1 small red onion, finely diced
• 1 plum tomato, diced
• 1 tbsp tomato purée
• 1 tsp ground cumin
• 1 tsp ground allspice
• 1 tsp ground coriander
• Pinch of turmeric
• Pinch of ground nutmeg
• ½ inch cinnamon stick
• 10g pine nuts
• Small glass of lager
• Small bunch of parsley, chopped
• 1 tbsp rapeseed oil
• Butter
• Pinch of sea salt

Method

Heat the oil in an ovenproof casserole dish over a medium heat. Add the onion with a pinch of salt and cook for 5 minutes until softened.

Add the tomato and tomato purée, stir, and cook for one minute.

Add all the spices and the cinnamon stick, stir, and cook for one minute more.

Pour in the beer.

Add the lamb and cook for 10 minutes until the meat is heated through and everything has come together. Turn off the heat, add the pine nuts and parsley, and stir gently. Allow it to cool.

Meanwhile, boil the potatoes, sweet potato and carrot in salted water until tender. Drain and mash with a generous knob of butter.

Spoon the mash over the cooled lamb and dot the top with a little more butter.

Place in a hot oven (200°C / 180°C fan) for 15 to 20 minutes, or until the top has started to brown.

This sweet potato shepherd's pie recipe is part of the Lamb & Goat collection — lamb and goat recipes from Casa Adora and the road.

This recipe is also part of the Slow Cooker & Slow Cooking Recipes collection — braised meat, one-pot casseroles, confit, and slow roasts from Casa Adora and the road, gathered in one place. Browse all recipes here.

Wonky photos, proper food, genuine adventures – The Flexible Chef