Unpeeled oranges (or other orangey citrus) to the weight of approx 375g
6 eggs
1 heaped teaspoon baking powder
1/2 teaspoon bicarbonate of soda
200g ground almonds
150g caster sugar (superfine sugar)
50g Dutch cocoa
Ganache:
200g dark chocolate
200ml cream
-Put the whole, unpeeled oranges in a saucepan with cold water to cover and bring to the boil. Cover with a lid and cook for 2 hours or until soft.
-Drain, and when cool, cut the oranges in quarters and remove any big pips.
Place everything - peel, pith and all - in a food processor.
-Cool the fruit before proceeding with the next step. Often it's best to complete the cooking of the fruit the day before.
-Preheat oven to 180C (350F) and line a 20cm springform (8-inch or standard) tin. Lining it is very important, if you want to remove your cake later; a double layer of paper is a good idea.
-Add the eggs, baking powder, bicarb, almonds, sugar and cocoa to the oranges in the food processor. Process until you have what looks like a cake mixture with a few knobbly bits of pureed orange.
-Pour and scrape into the cake tin and bake for an hour, by which time a skewer should emerge fairly clean. Start checking after 45 minutes, as you may have to cover with foil to stop the surface burning. It may take up to 1 1/2 hours to cook through, depending on your oven.
-Leave the cake to cool in its tin and remove when cold.
-To make the ganache, heat the cream in a heavy saucepan and add the chocolate off the heat. Mix until combined, then whisk until the mixture cools and becomes thick and glossy, ~5-10 minutes, and apply with a spatula or cake knife. Decorate with pieces of orange peel if you so desire.