Add the milk and dark chocolate to a saucepan with peanut butter and melt over low-medium heat.
In a separate medium sized saucepan add the milk and vanilla extract and heat over medium heat until heated through but not boiling.
Once heated add the drinking chocolate along with the melted chocolate and peanut butter mixture to the milk and whisk until all ingredients are combined, then let simmer for roughly four minutes, stirring constantly.
Smother the top of the serving glass or mug with peanut butter and roll the top in crushed pretzels.
Pour the peanut butter hot chocolate mixture in to the serving glass or mug and top with whipped cream and pretzel and serve immediately.