Preheat the oven to 375ºF.

Put the oranges in a pot with some cold water, bring to a boil and cook for 2 hours.

Drain and, when cool, cut each orange in half and remove the pits. Put the whole oranges - skins, fruit and all - in a blender and pulse.

Add the remaining ingredients and pulse until it becomes a pulp. Butter and line an 8 inch springform pan.

Pour the cake mixture into the prepared pan and bake for an hour. The cake is ready when a skewer will come out clean. You may have to cover with foil after about 40 minutes to stop the top from burning.

Remove from the oven and leave to cool, on a rack, but leave it in the pan. Take it out of the pan only when it is completely cooled.

Makes one 8" round cake.