Wash the navel oranges, cut off the ends (discard the ends) and place the oranges into a large pot.
Cover with water, bring to the boil on the stovetop, then simmer for 2 hours (add more water during this time).
Remove the oranges from the water and allow to cool completely (they'll be nice and soft).
Preheat oven to 160 degrees celsius (fan-forced). Grease and line the base and sides of a 22cm springform pan with baking paper and set aside.
Chop the cooled oranges into pieces and place into the TM bowl. Slowly increase to Speed 7 and continue to process until completely smooth (you'll need to scrape down the sides of the bowl occasionally). Set aside in a separate bowl.
Clean and dry the TM bowl. Add the eggs and caster sugar and mix for 30 seconds on Speed 5.
Add the orange puree and mix for 10 seconds on Speed 5.
Add the almond meal and baking powder and mix for 20 seconds on Reverse, Speed 3.
Pour the mixture into the prepared baking tin.
Sprinkle the flaked almonds over the top of the cake.
Bake for 60 minutes or until a skewer inserted into the middle comes out with just a few crumbs on it.
Allow to cool completely in the tin (preferably overnight) and store at room temperature.
Dust with icing sugar just before serving.