Heat the oven to 350°F. Place cupcake liners into cupcake pans.
In a large, heavy saucepan, combine the butter, oil, chopped chocolate, and 1 cup water. Heat over medium heat until melted and fully combined.
In a large bowl, whisk the flour, sugar, and cocoa powder. Pour the hot chocolate mixture into the sugar mixture and whisk until combined.
Whisk in the eggs, one at a time (making sure to keep whisking - you don’t want the eggs to scramble), then whisk in the buttermilk, vanilla, baking soda, and salt. Fill each cupcake liner about 2/3 full.
Bake cupcakes for 17-22 minutes, or until a toothpick comes out clean when inserted into the center. Cool on racks for 10 minutes.