• Preheat oven to 160C/325F. Line a muffin tin with 12 cupcake liners. Set aside.
• Combine flour, sugar, cocoa, baking powder, baking soda, salt and espresso powder in a large bowl and whisk to combine.
• In a smaller bowl, combine milk with vinegar, vegetable oil, egg and vanilla and mix to combine.
• Pour the wet ingredients into the dry ingredients and gently mix with a whisk (avoid using a stand mixer, or an electric beater to mix here- doing so will overwork the batter and will create tough cupcakes). .When nearly all combined, add the hot water and mix until combined (again, be careful not to over mix). The mixture will be very runny, this is good 🙂.
• Pour mixture into a pouring jug and distribute the batter between the cupcake liners (each should be about ¼ full).
• Place in the oven and bake 12-15 minutes or until a toothpick inserted in the center comes out clean.
• Remove from the oven and allow the cupcakes to cool completely before frosting.

To make chocolate buttercream:

• Beat butter and salt together for one minute. Sift in cocoa and continue beating until well combined. Gradually add icing sugar and vanilla and beat until light and fluffy.