Heat the oil in a large pan, sear the prawns for 3-5 minutes over a medium-high heat, until pink all over and showing colour, then remove from the pan.

Melt the butter in the same pan, cook the onion low and slow for 10-15 minutes, stirring regularly, deep brown in colour and jammy. Add the garlic, sauté for 2-3 minutes, stir in the tomato paste and cook for 2 minutes, until thick, pour in the stock, cream, stir to combine, bring to a low simmer and cook for 5-10 minutes whilst the pasta is cooking.

Boil a large saucepan of salted water and cook the spaghetti until al dente. When draining reserve a big bowl of pasta water.

Stir the parsley into the alfredo sauce, taste the sauce for seasoning, add salt and pepper if needed, toss in the spaghetti with pasta water as needed to create a glossy sauce that coats the spaghetti. Add in the parmesan and chilli oil if you wish and then you are ready to serve.