1. First make the pesto. Using a pestle and mortar, crush the garlic with 1/2 teaspoon of sea salt to a smooth paste. Add the basil leaves and pound so the leaves turn to a pulp. Add the pine nuts and crush until smooth. Add 3 tablespoons of water and emulsify, then add the Parmesan cheese. Finally, slowly work in the olive oil.
2. Cook the pasta with the courgettes in a large pot of boiling salted water for about 3 minutes - the pasta should still have a bite.
3. Meanwhile, warm half the pesto in a frying pan.
4. Using tongs, lift the pasta and courgettes from the water and add to the frying pan. Toss with the pesto and add 2-3 tablespoons of the pasta water to loosen the sauce so it coats the pasta strands.
5. Check and adjust the seasoning and serve with the remaining pesto on top.