Preheat the oven to 180°C. Line a 23cm cake tin with baking paper or grease and flour a 20cm x 30cm glass dish.
In a small bowl, mix the cocoa powder with the boiling water until smooth and set aside to cool.
In a large mixing bowl, beat the softened butter, sugar, vanilla essence until light and fluffy. Add the eggs, one at a time, beating well after each addition.
Sift in the Flour Mix, Baking Powder, and Baking Soda. Pour in 1 cup milk and mix well until combined.
Stir in the cooled cocoa mixture and beat until smooth. Pour the batter into the prepared tin or dish.
Bake for 45–60 minutes, or until a skewer inserted into the centre comes out clean. Allow to cool in the tin before turning out onto a wire rack.
Once cooled, sift icing sugar over the top or top with icing before serving.
