Chocolate Pudding with Salted Pretzels

This takes me back to childhood when the sound of a pull-tab popping on a can of Snack Pac made my heart sing, and I risked injury to my tongue just to lick off any little bits of pudding sticking to the top of the can. Now they are made from plastic... where's the fun in that???
Adapted from Bon Appétit magazine.

1 cup sugar
2 T cornstarch
2 T unsweetened Dutch-process cocoa powder
pinch of kosher salt
4 egg yolks
2 cups whole milk
1 cup heavy cream
1/2 vanilla bean, split lengthwise, or 1 t vanilla bean paste (much easier)
6 oz. bittersweet chocolate, melted (I used a combination of dark and bittersweet from Trader Joe's)
1 T unsalted butter
1 t vanilla
whipped cream and crushed pretzel thins (I just got to thinking that chocolate-covered pretzel thins or chocolate-covered potato chips from Trader Joe's might be divine) for topping

In a heavy saucepan, whisk the sugar, cornstarch, salt and cocoa powder. In a medium bowl, whisk yolks, milk, cream and vanilla bean (scraped stuff from the middle and pod) or vanilla paste. Whisk the milk mixture into the saucepan with the dry ingredients. Don't worry if you see some lumps of cocoa powder; they will go away.

Bring the mixture to a boil over medium-high heat, whisking constantly. Reduce heat and continue cooking and whisking for an additional 4 minutes. Remove from heat and add the melted chocolate, butter and vanilla extract. Strain through a sieve into another bowl. If you are lazy like me, you may be tempted to skip this step. I warn you not to-- there are teeny, tiny little lumpy bits (egg, I suppose) that remain in the sieve which would ruin the silky smooth texture of this pudding. Trust me on this point.

You can either leave the pudding in one large bowl or divide it up into prettier glasses or bowls for serving. Whichever way you choose, immediately press plastic wrap on the surface of the pudding so that you don't get that disgusting crust that forms almost right away.

Right before serving, top with whipped cream and crushed salted pretzel thins.