Make the Crust
Combine crushed pretzels with 4 tablespoons of melted butter and 2 tablespoons of sugar.
Scoop a heaping tablespoon full of crust mix into bottom of mini 4-ounce mason jars. Set aside.
Make the Filling
Whisk together the sugar, cocoa, cornstarch, and salt in a medium saucepan. Whisk in the milk and egg yolks.
Whisk over medium heat until the mixture comes to a low boil and becomes thick, resembling a pudding thickness, about 10 minutes.
Remove from heat and stir in remaining 2 tablespoons of butter and vanilla.
Place jars on sheet trays for easy transfer. Fill each jar about 3/4 full of chocolate cream, cover with plastic wrap.
Chill in fridge for at least 2 hours.
Before serving, top toffee pieces, fresh whipped cream and a drizzle of caramel sauce, if desired.