Preheat oven to 200 C / 180 C fan / Gas 6. Line a 12-hole muffin tin with paper cases.
In one bowl sift together flour, cocoa, salt and baking powder. In separate bowl cream the sugar and butter, then beat in the egg. Add the dry ingredients to the butter mix, alternating with milk until the entire mixture is combined. Spoon the mixture into the paper cases, filling only to 3/4 to ensure a good rise.
Bake for 23 to 25 minutes on the centre rack of the oven until risen and firm and a skewer inserted into the centre comes out clean. Remove from the oven and allow to cool completely before decorating, if desired.