Bring a large saucepan of salted water to the boil and cook the pasta according to packet instructions. Before draining reserve a little of the pasta cooking water.

Meanwhile, in a large pan, I prefer to use a wok as it can easily take the cooked pasta later, add the oil. Using a fine grater, grate the garlic into the cold oil. Then zest the lemon directly into the pan and add the chopped chilli.

Turn a high heat on under the pan stir with a wooden spoon until it begins to sizzle then add the harissa. Stir again for a moment before adding the king prawns. Cook the prawns for 2 -3 minutes then add the spinach and stir until the spinach is wilted and the prawns cooked through.

Add the cooked spaghetti to the pan along with a tablespoon of the reserved pasta cooking water until the scant amount of fiery sauce coats the pasta. Add a little sea salt and give a final toss together before splitting between two bowls and serving.