Ingredients
800g/1¾lb sweet potatoes
55g/2oz butter
1 egg, beaten
salt and freshly ground black pepper
250g/9oz plain white flour
pinch of nutmeg
For the sauce:
200g/7oz mascarpone cheese
150g/5oz gorgonzola cheese
300g/10½oz young leaf spinach
toasted pine nuts (optional)

Method
1. Peel, chop and boil the sweet potatoes until very tender.
2. Pass the potatoes through a potato ricer and, whilst still warm, add the butter, egg, nutmeg, salt and pepper and about half of the flour.
3. Knead gently on a floured board and gradually knead in the remaining flour to form a fairly sticky but smooth dough.
4. Roll the dough into sausages, about 2cm/¾in thick. Cut into small 2cm/¾ squares. Roll each piece into a ball and flatten slightly with a fork. Toss very gently in a little flour.
5. Bring a large pan of salted water to the boil and cook the gnocchi in batches, removing them as they rise to the surface (about 2-3 minutes).
6. Meanwhile, make the sauce. Melt the mascarpone over a low heat and add the gorgonzola in 1cm/½in cubes.
7. When the gorgonzola has melted, gradually stir in the spinach leaves and wait until they have wilted slightly. Check for seasoning.
8. Toss the gnocchi in the sauce and sprinkle with toasted pine nuts, if desired. Toss again and serve.