Heat the oil in a very large saucepan, add the onion and cook for 2-3 minutes until softened. Then add the potatoes and cook out to the point where they start sticking to the pan – about 3-4 minutes. Add the garlic, thyme and chilli and stir.
Add the pasta and a ladleful of the stock and allow it to incorporate. Keep adding the stock a ladleful at a time, stirring and allowing it to reduce each time, as you would with a risotto, until all the stock has been used. This should take about 10 minutes.
Add the beans then stir in the rocket, Parmesan and basil and season to taste with salt and pepper. Serve with more Parmesan sprinkled on top.