Parboil the asparagus in well-salted water until crisp-tender, about 5 minutes. Drain and let them cool off of their own accord.

Then, taking three or so spears of asaragus as a time, wrap them in 2 or 3 slices of pancetta, making little bundles out of them. Lay them as you go in a greased baking dish just big enough to fit all the asparagus is a single layer, crease side down. (NB: There is no need to tie them up so long as you are careful about handling them.)

Melt the butter and either brush or spoon it over the asparagus bundles. Then sprinkle over the cheese if using.

Bake in a hot oven (200C/400F) for about 20-30 minutes, until the the pancetta has lightly browned. (Using the convection function will make things go faster, if you have it.) Remove from the oven and let it cool for just a couple of minutes, then serve immediately, carefully transferring the little bundles with tongs to hold them together on to plates. Spoon over a bit of the juices left in the baking dish.