British Beef Cottage Pie with Sweet Potato Mash

Instructions

1. 1

   Heat the oven to 200°C fan / 220°C conventional.

2. 2

   Tip the sweet-potato chunks into a saucepan, cover with cold water, and bring to a boil. Cook for 12 to 15 minutes, until a fork slides in easily. Drain in a colander and leave to steam-dry for 3 minutes — wet mash will not hold peaks.

3. 3

   While the potato cooks, heat the olive oil in a wide ovenproof skillet (or large frying pan) over medium-high heat. Add the onion, carrot, and celery and cook for 6 to 8 minutes, stirring often, until the onion is soft and translucent.

4. 4

   Add the chopped garlic and dried thyme, stir for 30 seconds until fragrant, then add the lean beef. Break it up with a spoon and cook for 6 to 8 minutes, stirring often, until no pink remains and any liquid has cooked off.

5. 5

   Stir in the tomato paste and cook for 1 minute, then sprinkle over the plain flour and stir for 30 seconds. Pour in the Worcestershire sauce and the beef stock, scrape the bottom of the pan, and bring to a simmer.

6. 6

   Simmer uncovered for 8 to 10 minutes, stirring occasionally, until the sauce thickens enough to coat the back of a spoon. Stir in the frozen peas with 1/4 tsp of the salt and the black pepper, then take off the heat.

7. 7

   Tip the drained sweet potato into a bowl, add the butter and semi-skimmed milk, and mash with the remaining 1/4 tsp salt until smooth and thick — it should hold soft peaks when you lift the masher.

8. 8

   Transfer the beef filling to a 22 x 30cm ovenproof baking dish (or leave it in the ovenproof skillet). Spoon the sweet-potato mash evenly over the top and rake the surface with a fork to make peaks that will brown.

9. 9

   Bake for 18 to 22 minutes, until the mash peaks are golden and the filling is bubbling at the edges. Rest for 5 minutes before serving so the filling sets enough to spoon cleanly.