Pre heat oven to 180°C/165°FF/350°F
Line a cupcake pan with paper liners
In a stand mixer, beat the butter and sugar on medium for 5 minutes.
Add the egg and beat until combined.
Into a bowl, sift together the flour, cocoa and baking soda.
Add salt to the buttermilk.
Alternating between the 2, add the combined flour/cocoa/soda and the buttermilk/salt to the stand mixer in batches, beating on low until just combined.
Stir in the food colour, vanilla and vinegar and beat until just combined.
Using a large ice cream scoop, scoop the batter into the 12 paper liners.
Bake for 20 minutes, until an inserted skewer comes out clean.
Cool the cupcakes in the pan for 10 minutes, then cool completely on a cake rack, before frosting them.