In a small bowl, whisk together the sugar, cocoa powder, and salt until no lumps remain.
Pour the milk into a medium saucepan placed over medium-low heat.
Whisk the dry cocoa mixture into the milk continuously until fully dissolved and smooth.
Heat the mixture until it is steaming and hot, but do not let it come to a rolling boil.
Remove the saucepan from the heat.
Stir in the peppermint extract and vanilla extract.
Pour immediately into mugs.
Top with a generous dollop of whipped cream and sprinkle with crushed peppermint candies before serving.