In a medium hot frying pan, add onion and fennel to sweat off. Then add garlic and chilli and cooked king prawns. Stir together well then add a splash of white wine and cook for a further 3-5 minutes.
When the pasta is ready, add it to the pan with some of the pasta water, squeeze half a lemon and add its zest and combine together with salt and pepper for seasoning. Sprinkle with fresh basil.