Preheat oven to 350˚F. Prepare baking pans (see below for possible yields).
Whip eggs on stand mixer with whisk attachment until foamy and doubled in size.
Melt the chocolate in the microwave, stirring every 10 seconds.
Pour one-fourth of the coffee/espresso over the chocolate and stir till incorporated, then add the rest.
Sift and combine dry ingredients.
Have all ingredients ready (the dries, chocolate coffee liquid, buttermilk, vanilla, oil, and sugar).
Once eggs are foamy, add the sugar, followed by the oil and vanilla, followed by the chocolate mixture. Whisk till combined.
Alternate adding the dries and buttermilk slowly (dry, buttermilk, dry, buttermilk, dry).
Fold the mixture together a few times, being sure the sides and bottom are all homogeneous.
TO BAKE: Be sure to rotate your cake halfway through the time to ensure it bakes evenly! 13”x9” will take 30 minutes; two 8” rounds will take 30 minutes; and 24 cupcakes will take 15 minutes.