Bring a large pan of water to the boil. Cook the pasta according to the packet instructions, drain and reserve 50ml of the cooking water.
Meanwhile, heat the oil in a large frying pan, add the asparagus tips and cook over a gentle heat for about 3–4 minutes until they start to soften. Add the garlic and chilli flakes and cook for a few seconds. Stir in the pine nuts and cook for 1 minute.
Add the drained pasta to the pan and toss well. Then add the lemon zest and juice, the reserved cooking liquid, a pinch of salt and a good grind of black pepper. Toss in the pecorino and parsley and serve.