For the topping:
500g floury potatoes, such as King Edward or Maris Piper, peeled, cut into pieces
300g parsnips or swede, peeled, cut into pieces
knob of butter
splash milk
salt and freshly ground black pepper
For the filling:
1 tbsp rapeseed or groundnut oil
1 onion, peeled, finely chopped
1 garlic clove, peeled, crushed to a paste with the edge of a knife
1 large carrot, peeled, finely chopped
1 leek, trimmed, thinly sliced
2 tsp chopped fresh thyme leaves
300g/10½oz vegetarian mince, fresh or frozen
400g/14oz can cannellini beans, drained and rinsed
400g/14oz can chopped tomatoes
1 tbsp tomato purée
sugar, to taste (optional)
salt and freshly ground black pepper
steamed green vegetables, to serve
Preheat the oven to 190C/170C Fan/Gas 5.
To make the topping, place the potatoes and parsnips or swede into a large pan of water. Bring to the boil and cook for 12–15 minutes, or until tender. Drain well.
Add the butter and mash using a potato masher or ricer. Add the milk, a little at a time, and continue to mash until smooth. Season, to taste, with salt and freshly ground black pepper. Set aside.
To make the filling, heat the oil in a large pan over a low to medium heat. Add the onion and fry for 10 minutes, or until softened. Add the garlic, carrot, leek and thyme and continue to fry for a further 5 minutes, or until softened. Add the vegetarian mince to the pan and fry for a further 3 minutes, stirring continuously, or until golden-brown.
Add the drained cannellini beans, chopped tomatoes and tomato purée and stir well to combine. Simmer for 5 minutes, or until the sauce has thickened. Season, to taste, with salt and freshly ground black pepper. Taste and add a little sugar to the mixture if needed.
Spoon the filling into a large ovenproof dish. Spread the mashed potato and parsnip (or swede) mixture over the filling in a smooth, even layer.
Bake for 20 minutes, or until the topping is golden-brown and the filling is cooked through. Serve with steamed green vegetables.