First, gather your ingredients - coffee beans, milk, and a hot chocolate ball. You want to work quickly so the espresso and milk stay warm enough to melt the chocolate. (The best way to do this if you don't care about watching the "bomb" explode it to make the espresso right into a mug with the hot chocolate bomb in it to start melting the chocolate right away.)
If you want to get the full effect of the exploding cocoa ball, place a hot chocolate bomb in a large mug.
Next, make two shots of espresso (about 2 ounces of coffee) or heat a shot glass (or two) worth of Bailey's Irish Cream. (For detailed instructions on how I make espresso, see the notes above.)
Now, steam the milk right away - save the cleanup for later. Steam the milk warmer than you would normally do for a latte to help melt the chocolate. (If you are making this for kids (decaf) or someone who might accidentally burn themself, let it cool before serving it to them.)
Now, pour the espresso over the chocolate ball, then the milk immediately after - trying to save a little foam if you can to top it off.
Then stir until the chocolate is dissolved. Top with leftover foam or some whipped cream.