Cut the rock melon in half and, using a dessert spoon, scrape away the seeds from the middle of each half and discard.
Slice each half into half, and then half again, so that you have 8 slices.
Take each slice and, using a paring knife, carefully slice the melon away from the rind, leaving about an inch uncut at one end - this makes it easy to eat the melon, while ensuring it doesn't fall off the rind.*
Put 4 serving plates on the counter, and place 2 slices on each plate. Then drape a rasher of prosciutto over each piece to serve.
Notes
*You can, of course, cut away the whole rind if you prefer, however it's quite nice to serve the melon on the rind.
Recipe by The Kiwi Cook at https://thekiwicook.com/2017/02/21/rockmelon-cantaloupe-with-prosciutto/