Preheat the oven to 180°C. Line 24 muffin tins with cupcake papers.
Sift flour, sugar, cocoa, baking soda, baking powder and salt into a bowl and set aside.
Combine the milk, vinegar, coffee, oil and peppermint extract in another bowl. Beat in the eggs one at a time until well combined.
With the mixer on low, carefully add in the dry ingredients. Mix until combined (the batter will be very thin).
Fill cupcake liners about ⅔ full with mixture and bake for 20 minutes or until a skewer comes out clean.
Allow to cool in the tin for 15 minutes, then turn out onto a wire rack.
Hold your cooled cupcake in one hand and insert a small knife, at an angle, and cut out a cone shaped piece out of the centre of each cupcake.