In a saucepan over medium heat, combine milk and heavy cream. Heat until warm but not boiling.
Stir in dark and white chocolate chips, whisking until melted and smooth.
Add cocoa powder, vanilla, and peppermint extract. Continue stirring until creamy and steamy.
Pour into mugs.
Top with whipped cream, festive sprinkles, crushed peppermint, or mini marshmallows.
