Put a 30cm non-stick frying pan on a medium-high heat. Peel and finely slice the garlic and place most of it in the pan with a little drizzle of olive oil and the gnocchi. Fry for 5 minutes, tossing occasionally, while you pound the remaining garlic with the hazelnuts in a large pestle and mortar. Pound in the spinach (in batches, if needed), loosen with a little extra virgin olive oil, finely grate in most of the Parmesan and season to perfection.
Scrunch the tomatoes into the pan through clean hands, and add ½ a tin’s worth of water. Simmer for a couple of minutes until thickened, and season to perfection. Snap the woody ends off the asparagus, nestle the spears into the sauce, then cover and steam for 5 minutes, jiggling the pan occasionally. Squash and destone the olives. Serve the gnocchi and asparagus with a dollop of pesto, then tear over the olives and finely grate over the remaining Parmesan, to finish.