Step 1

Place the oil and half the butter in a saucepan over medium-low heat. Once the butter has almost melted, add the garlic and rosemary and cook, stirring, for 1-2 minutes until fragrant. Add the leeks and cook, stirring, for 8-10 minutes or until very soft but not coloured. Pour in stock, then lay prosciutto slices over the leeks to cover completely.

Step 2

Reduce the heat to low and cover witha lid. Cook for 15 minutes or until the prosciutto is just starting to dry out. Remove the lid and cook for a further 10 minutes, checking occasionally and adding a little boiling salted water if becoming too dry, until the leeks have broken down and the prosciutto is soft.

Step 3

Use 2 forks to shred the prosciutto, then stir through the leeks. Stir in the remaining 30g butter.

Step 4

Meanwhile, cook the pasta in boiling salted water according to packet instructions until al dente. Drain.

Step 5

Add the pasta to the leek and prosciutto, season with sea salt and pepper, and toss to combine. Divide among 4 bowls, sprinkle over pecorino and parsley, then serve immediately.