Preheat the oven to 350°F.
Line a 12-hole cupcake tin with cupcake liners.
In a large bowl add the flour, cocoa powder, sugar, baking powder, salt and butter.
Use a handheld electric mixer or the paddle attachment fitted to a stand mixer to thoroughly mix together. The mixture should have a sandy consistency.
In a separate bowl, beat together the milk, eggs and vanilla extract.
Slowly pour the wet ingredients into the dry ingredients. Beat on high speed and beat well for a couple of minutes or until the cupcake batter is smooth.
Divide the cupcake batter between the 12 cupcake liners.
Bake in the center of the preheated oven for 18-20 minutes or until the cupcakes bounce back when touched with a finger.
Remove from the oven and leave to cool completely on a cooling rack.