Preheat oven to 180 °C.
1 In a medium bowl, mix together 200 ml (3⁄4 cup) caster sugar, the flour, 45 ml (3 tbsp) cocoa, baking powder and salt. Whisk in the milk, butter and vanilla. Beat until smooth.
2 Spread this batter in a greased baking pan. Sprinkle with chocolate.