Put a mason jar in the freezer (this is for making the cream topping. If you'd rather use whipped cream, skip this step).
Make a pot of strong coffee.
While the coffee is brewing, make yourself a batch of hot chocolate. We recommend something homemade and creamy, but any hot chocolate will work.
Pour your hot chocolate into the bottom 1/3rd of your mug.
Pour your coffee over the back of a spoon into the mug, filling to 2/3rds full.
Put your heavy cream into the chilled mason jar and close.
Shake until the cream thickens slightly.
Pour cream over the back of a spoon, filling the mug completely.
Top with chocolate shavings.
Notes
To make this drink easier, you can skip the layering and just pour things in, instead of pouring over the back of a spoon. Using whipped cream instead of whipping your own "partial" whipped cream would also save time.