Blanch the spring onions for approx. 30 secs. in boiling salted water, remove with a slotted spoon, briefly dip in ice-cold water, pat dry. Separate the spring onions into approx. 8 strips.
Mix the asparagus with the oil and salt, divide into 8 equal-sized bunches. Wrap the asparagus bunches in 1 strip of spring onion and 1 rasher of bacon, transfer to a baking tray lined with baking paper. Scatter the cheese over the top.
Approx. 20 mins. in the centre of an oven preheated to 200°C.