In a medium saucepan, combine 2-3 cups of whole milk and ½ cup of heavy cream over medium heat. Stir gently until steaming but not boiling, about 3 minutes.

In a small bowl, whisk together ½ cup of cocoa powder and 1-2 tablespoons of grated chocolate. Gradually mix in ½ cup of the warm milk mixture until smooth.

Slowly pour the chocolate mixture back into the saucepan with the heated milk while whisking constantly. Add the sweetened condensed milk and ⅛ teaspoon of vanilla extract, whisk for 3 minutes.

Reduce heat to low and let the hot chocolate simmer for 3-5 minutes, stirring regularly until thick enough to coat the back of a spoon.

Ladle the hot chocolate into mugs and top with whipped cream and a sprinkle of ground cinnamon. Serve hot.