To make a bicerin, warm one cup (250 ml) whole milk in a medium-sized saucepan with 3 ounces (90 gr) of chopped bittersweet or semisweet chocolate. Whisk the mixture until it begins to boil, then let it boil for 1 minute, whisking constantly (the chocolate mixture will foam up a bit.)
Afterward, remove it from the heat and set aside. Make a small pot of very strong coffee, or good Italian espresso.
Fill the bottom third of a clear, heat-proof glass with the warm chocolate mixture. Pour in some coffee or espresso. (If you want to help it create a definite layer, pour it over the back of a spoon, into the glass.)
Top with a nice swirl of sweetened, freshly-whipped cream.