01 - In a medium saucepan over medium heat, combine whole milk, heavy cream, and vanilla extract. Warm until steaming, taking care not to bring to a boil.
02 - Whisk in chopped dark chocolate, Dutch-processed cocoa powder, granulated sugar, instant espresso powder, and a pinch of sea salt. Continue whisking until the chocolate is fully melted and the mixture becomes smooth and velvety.
03 - Reduce heat to low and allow the mixture to gently simmer for 2–3 minutes, stirring frequently to prevent scorching.
04 - Taste and adjust the sweetness, adding more sugar as needed to suit your preference.
05 - Pour the hot chocolate into heatproof mugs. Top with whipped cream and dark chocolate shavings if desired. Serve immediately while hot.