Preheat the oven to 350 degrees F. Line a muffin pan with 12 paper liners.
Place the boiling water, cocoa powder and instant coffee in a small bowl. Whisk thoroughly to combine until smooth, then set aside to cool.
In a large mixing bowl, add the vegetable oil, eggs, buttermilk, granulated sugar and vanilla extract. Whisk for 2-3 minutes until the mixture is well combined.
Add the cooled chocolate mixture to the large bowl, and whisk again until fully incorporated.
Set a sieve over the mixing bowl, and sift in the flour, baking powder, baking soda and salt. Use a spatula to gently fold the ingredients together, being careful not to overmix. The batter will be runny with a few lumps.
Divide the cake batter between the 12 muffin cups, each cup should be about ¾ full.
Bake in the middle of the preheated oven for 18 minutes or until a toothpick inserted into the center comes out clean.
The cupcakes will have risen slightly over the edges of the liners and should feel springy to the touch. Set aside to completely cool.