Line the muffin tin with cupcake cases and set it aside. Preheat the oven to 180C/350F whilst making the red velvet cake batter.
Beat the butter in a mixing bowl for 4-5 minutes until really soft and paler. Add in the caster sugar and beat again until really pale, light and fluffy.
In a separate jug, whisk the eggs together with the vanilla and food colouring. Gradually add the egg mixture in with the butter and sugar, beating between additions, until fully incorporated. Make sure to scrape down the bowl to ensure everything is well combined.
In the same jug the eggs were mixed in, combine the milk and yogurt to make buttermilk. In another clean bowl, sift and combine together the flour, cocoa powder and baking powder.
Add the flour to the egg mixture in three additions, alternating with the buttermilk, and mixing on a low speed only until just combined. Scrape down the bowl again to make sure all the ingredients have been incorporated.
In a small clean bowl, combine the bicarbonate of soda (baking soda) and vinegar. It will bubble together when combined. Quickly tip this into the cake batter and fold through until completely mixed in.
Divide the mixture evenly between the twelve cases, filling them about ⅔ full. Place in the preheated oven and bake for 25-30 minutes until the cupcakes are risen, springy to touch and a toothpick inserted comes out clean. Leave to cool in the tin for five minutes, then remove and place on a cooling rack to cool completely.