I do. If you are looking for a mocha flavor use more; if something to boost or add backgroound to the chocolate use less. Start with 1-2 Tblsp.
I prefer dried instant espresso. It is available in jars, but can be hard to find. Look at WF or HT. If you can't find that, or for another alternative, try Starbucks Via instant coffee (in packets) - the dark roast.