To make the cupcakes:

1. Preheat the oven to 350 degrees and line two 12-cavity muffin pans with 18 paper liners. Set aside.
2. Add the hot coffee to a measuring cup and whisk in the black cocoa, natural cocoa, peppermint extract and vanilla extract until blended and smooth. Set aside.
3. Add the oil to the buttermilk and whisk well until blended together. Set aside.
4. In a large mixing bowl (large enough to hold the entire batch of batter, I used a 3 quart bowl) add the egg, yolk, sugar, salt and baking soda. Whisk vigorously for one minute until lighter in color and smooth.
5. Add the buttermilk/oil mixture and whisk for another minute.
6. Add the flour and whisk well for 2 minutes. Add the coffee/cocoa/extract mixture and melted dark chocolate and whisk for a minute to fully combine.
7. Divide the cake batter evenly among the prepared cupcake pans, each cavity should get 3 TB of batter. Bake the trays for 22-24 minutes each, my cupcakes always take 23 minutes. Keep an eye on the temperature of your oven and start checking for doneness at around 21 minutes. The tops of the cupcakes should spring back lightly when pressed with your finger.
8. Allow the cupcakes to cool completely before frosting.

To make the mint fudge frosting and finish the cupcakes:

1. In a medium saucepan (I used a 3 quart size) combine the whole milk, butter, salt, peppermint extract, corn syrup and powdered sugar. Heat over medium low, whisking frequently, until the butter has melted into the milk and the powdered sugar has dissolved. Allow the mixture to scald, you should see wisps of steam just barely come off of the surface.
2. Remove the saucepan from the heat, and add the dark chocolate to a medium heatproof bowl. Pour the hot milk over the chocolate and allow it to stand together for 2 minutes.
3. After 2 minutes, whisk the chocolate mixture until all the chocolate has melted and the mixture is smooth. Have patience, it may take 5 minutes or so for everything to meld together. If the chocolate isn’t melting all the way, carefully microwave the mixture on half power for 15 second intervals, whisking well in between each one JUST until all the chocolate has melted. Don’t overheat the mixture or it will seize and break.
4. Refrigerate the chocolate mixture for 1 hour, stirring every 15 minutes until the frosting is firm enough to be pipeable/spreadable. It may take less than an hour, keep an eye on the consistency each time you stir and adjust the time accordingly.
5. Frost each cupcake with a few tablespoons of fudge frosting and serve immediately. You can refrigerate any leftover cupcakes for up to 3 days before they begin to dry out a bit.