Heat up a griddle or chargrill pan, then grill the corn for about 10 minutes, until charred all over.
Slice the kernels off the cobs with a sharp knife and reserve the cobs.
Put a large saucepan of water on to boil for the pasta and add a tablespoon of salt and the reserved cobs – they will add flavour to the pasta.
Boil the pasta for eight to 10 minutes, or according to the packet instructions, then drain, reserving a little of the cooking water and discarding the cobs.
Meanwhile, pour the olive oil into a frying pan and put it on a low heat.
Add the garlic, chilli and lemon zest, and leave to gently infuse for a couple of minutes.
Add the prawns, turn up the heat and cook for three to four minutes.
Add the drained spaghetti, corn and a splash of pasta water, and toss vigorously.
Season with salt and pepper, if required, and serve at once.
