Bring a large pan of salted water to a rolling boil. Blanch the asparagus for 3 minutes until just tender, then remove with kitchen tongs to a colander and immediately cool under running cold water. Drain briefly, then transfer to a chopping board. Cook the fusilloni in the asparagus water according to pack instructions.
Slice the tips off the asparagus and set aside. Roughly chop the stems and place into the bowl of a food processor with the pistachios, pecorino, garlic, dill, oil and lemon juice, then season. Blitz to a coarse paste.
Drain the pasta, then mix with the pesto and reserved asparagus tops. Divide between 2 warmed bowls and serve with an extra sprinkling of pecorino, if liked.
