Preheat oven to 350. Line cupcake pans with 24 liners.
Place cocoa powder in mixer bowl and pour scalding hot coffee over. Mix on low speed until a thick paste forms and mixture stops steaming- about one minute.
Turn mixer speed to medium. In a measuring cup, combine buttermilk, egg, yolk, vanilla, salt and oil, and mix lightly with a fork, ensuring yolks are broken. Slowly pour into mixer.
Stop mixer, detach paddle, and scrape bottom well to loosen any caked on cocoa. Reattach and turn mixer to medium, letting run one minute. Stop mixer again.
Sift together dry ingredients and pour into wet mixture. Mix on low speed til just combined. Remove bowl, and use paddle attachment to scrape down the sides of the bowl, ensuring everything is mixed.
Scoop cake batter into prepared pans, filling cups 2/3 of the way.
Bake in the middle of the oven for 20-25 minutes, rotating halfway through. Cupcakes are done when the centers spring back when you touch them.
Remove cupcakes from oven. Let cool completely.
Peanut Butter Buttercream: For French buttercream (recommended): Prepare master recipe for buttercream. Once butter is added, add peanut butter and kosher salt and mix on high to combine. Taste for seasoning.
If desired, add more peanut butter a tablespoon at a time, or a pinch more kosher salt. Continue until after tasting your eyes roll into the back of your head.
For American frosting: prepare master recipe, reducing sugar by 1/2 cup, replacing mascarpone cheese with peanut butter, and adding kosher salt. Once combined, taste for seasoning. Add more sugar or peanut butter if desired.
Classic Ganache: Place chocolate in a bowl, and shake back and forth until it flattens out on top.
Heat cream and sea salt in a medium saucepan until it comes to a boil.
Immediately pour hot cream mixture over chocolate, and allow to sit for two minutes to allow chocolate to melt.
Using a heatproof spatula, stir the cream and chocolate together until completely smooth.
Allow to cool slightly before drizzling on cupcakes. Ganache should not be hot to the touch, but still be liquid. If it cools completely and becomes solid, microwave on 50% power in 20 second increments, stirring between each, until desired consistency is reached.
Assembly: Fill pastry bag fitted with regular tip with peanut buttercream, and pipe onto each chocolate cupcake. Put cupcakes into the refrigerator so buttercream hardens- about 20 minutes.
Pulse pretzels and peanuts in a food processor until they're coarse crumbs. Alternately, place in a strong ziptop bag and repeatedly smack with a rolling pin, a heavy skillet, or anything else your find enjoyable. Place crumbs in a pie dish or baking pan.
Gently roll the sides of the buttercream in peanut/pretzel mixture. Pour a handful over the top and lightly pack on with hand. Shake off excess and set aside.
Drizzle ganache across each cupcake.
