Warm the milk in a small pot over medium heat until it steams and small bubbles form at the edge, about 3 minutes. Don't let it boil.
Whisk in the cocoa, chopped dark chocolate, maple and salt until the chocolate melts and the milk is smooth, about 1 minute.
Take the pot off the heat and stir in the peppermint extract. Taste and add a drop more if you like it cooler.
Pull your espresso into a mug, or pour in the strong coffee.
Froth the chocolate milk with a whisk or handheld frother for 20 seconds, then pour it over the espresso.
Top with the whipped cream and dark chocolate shavings and serve right away.