I learnt this technique for cooking asparagus from one of the nonnas I met at the market in Rome. By frying, then adding a little liquid and reducing to a low temperature, you ensure the flavours combine beautifully. Creating emulsification at the very end gives a perfect sauce that's as much about flavour as it is texture.
Cook the pasta in a pan of boiling salted water according to the packet instructions. Meanwhile, snap off and discard the woody ends of the asparagus, then finely slice the spears at an angle, leaving the tips whole. Peel and finely slice the garlic, crumble up the dried chillies, and place both in a large frying pan on a medium heat with 2 tablespoons of oil and the butter. When the garlic starts to sizzle, stir in the asparagus. Let it start to fry, then add a spoonful of pasta water, cover, and leave to simmer on a low heat until the pasta is al dente.
Using tongs, drag the pasta straight into the asparagus pan, letting a little starchy cooking water go with it. Turn the heat off, then finely grate in the pecorino and toss together until the fat, cheese and liquid make a natural creamy sauce--loosen with a little extra cooking water, if needed. Taste and season to perfection, then divide between your plates. Finish with a grating of pecorino and a little lemon zest, to taste.