Step 1

Parboil two thirds of the pistachios, discarding any papery skin. lightly toast and finely crush the remainder. cook the spring onions with the speck in a little butter till soft but not coloured.

Step 2

Blitz the parboiled nuts with the spring onions, speck and a little of the oil in a food processor, then stir the resulting paste, crushed nuts, parmesan and remainder of the extra-virgin olive into the ricotta.

Step 3

Cook the pasta and drain, leaving a little of the cooking water in the saucepan. stir in the pistachio sauce and serve with more grated parmesan.