I found this fantastic recipe on bakeplaysmile.com. It is a superb recipe and so simple to make. You can prepare the oranges the day before as that is the time consuming part.
Ingredients
• 2 navel oranges (or 3 small ones)
• 6 eggs
• 250g caster sugar
• 250g ground almonds (almond meal)
• 1 tsp baking powder
• 50 g flaked almonds
• 2 tbsp icing sugar for sprinkling
Instructions
1. Wash the navel oranges, cut off the ends (discard the ends) and place the oranges into a large pot
2. Cover with water, cover with lid and bring to the boil on the stovetop for 2 hours (add more water during this time if needed)
3. Remove the oranges from the water and allow to cool completely (they'll be nice and soft)
4. Preheat oven to 160 degrees Celsius
5. Grease and line the base and sides of a 22cm springform pan with baking paper
6. Chop the cooled oranges into pieces and place into a food processor or blender (I use a blender as it creates more of a paste)
7. Process until completely smooth and no lumps remain. Set aside
8. Beat the eggs and caster sugar in a large bowl until pale and frothy
9. Add the orange puree and stir through with metal spoon
10. Fold in the ground almonds and sifted baking powder
11. Pour the mixture into the prepared baking tin
12. Sprinkle the flaked almonds over the top of the cake
13. Bake for 60 minutes or until a skewer inserted into the middle comes out with just a few crumbs on it
14. Allow to cool completely in the tin (preferably place it into the fridge overnight
15. Sprinkle with icing sugar just before serving