Here is a goal: How to quickly melt chocolate?

Which way makes more sense to accomplish this goal?

OPT: [-] use chocolate slabs and place them under a double boiler, as the chocolate starts to melt, add a little water and stir [-] use chocolate nibs and place them over a double boiler, as the chocolate starts to melt, add a little milk and stir
use chocolate nibs and place them over a double boiler, as the chocolate starts to melt, add a little milk and stir