This is a really easy cake ... perfect for the girls to make.
Grease a 20 cm cake pan and line with baking paper. Preheat the oven on moderate.
Wash and dry a whole orange, cut into quarters, remove the seeds and process to pulp in a food processor.
Mix in a bowl the orange pulp, 200g melted butter, 1 cup castor sugar and 1 1/2 cups self-raising flour. Pour into prepared pan and bake for 50 mins. Stand for 10mins before turning out of the tin.
You can sprinkle with icing sugar or ice with orange icing.