Preheat the oven to 180°C.
Sift together flour, cocoa powder, and baking powder.
Cream the butter and sugar together.
Add eggs one at a time, mixing well after each addition.
Alternately add the sifted dry ingredients and milk to complete the batter.
Pour the batter into a cake pan.
Bake in the oven at 180°C for 25 to 30 minutes.
Cool completely, then decorate as desired.