This is really similar to the Whole Orange Cake in the EDC but it's gluten free too, and it has chocolate which makes it doubly delicious! It got rave reviews at the office!Ingredients 1 litre water (1000g) 
2 small thin-skinned oranges, or 1 large (about 375g in weight) 
1 teaspoon baking powder 
1/2 teaspoon bicarbonate of soda 
200g almonds 
250g  raw sugar 
6 eggs 
50g cocoa 
How to 1. Place water into TM bowl. Insert the steaming basket and put the whole oranges into the basket. Cook for 
45 minutes  on Varoma temperature on 
speed 3. When the oranges are ready, set aside until cool enough to handle.
 2. Preheat oven to 180C / 160C fan-forced. Grease and line a 23cm springform pan.
 3. When the oranges are cool, cut into quarters, remove the pips and cut off  the knobbly, gnarly bits of peel at either end.
 4. Mill the raw sugar to caster sugar  for
 3 seconds   on
 speed 9. Set aside.
 5. Put the almonds into the TM bowl and mill for 
10 seconds  on
 speed 9. Add the remaining ingredients, including the sugar and the orange pieces to the TM bowl. Mix for
 20 seconds   on 
speed 7.
 6. Pour the mixture into prepared tin and bake for approximately 40-45 minutes  or until a cake tester comes out clean. If it’s still not ready after 45 minutes, cover with foil to prevent it from burning.
 7 .Leave the cake to cool in the tin on a cooling rack.
 8. Remove from the cake from the tin when cool. Decorate with some grated orange zest, candied orange peel or if you really want to push the boat out, some chocolate ganache. However, this cake is stand alone delicious and is divine even when undecorated.
More pics on the blog 
http://www.theannoyedthyroid.com/2013/07/18/nigellas-flourless-chocolate-orange-cake-in-the-thermomix/