Lay a slice of prosciutto flat between two pieces of paper towel.
Place flat in the microwave, and microwave on full power for 30 seconds, then remove immediately and remove paper towel (the paper towel will be damp).
The prosciutto will be quite crisp when removed from the microwave, but will continue to crisp on standing.
Notes
The prosciutto will pop and crackle a bit in the microwave, this is normal. Plus when you open the microwave door, it will be full of steam - again, this is normal.
You can even use frozen slices of prosciutto for this method of cooking, I do it all the time (see my next point).
Prosciutto can be expensive, so I buy it when it's at a special sale price then freeze it flat with pieces of baking paper in between and wrapped in plastic wrap. This means I always have a stash in the freezer.
This cooking method can bring out the saltiness (in a good way!) in the prosciutto, so I would bear that in mind when you decide what dish you are going to use it in and how much salt you include.
*Please note that the amount of calories per serve is provided as a guide only, as ingredients and cooking methods can vary greatly*