In a medium saucepan, add oranges and cover with water. Bring it to a boil, then cover and reduce heat to low and simmer for an hour until the oranges are soft.
When oranges have cooled, cut in half, remove any seeds and place in a blender. Pulse until smooth. Decant and measure out 1½ cups of the orange puree. If you have extra, store in a ziploc in the freezer for next time.
Preheat the oven to 170°C fan force.
Return orange puree to the blender and add the polenta, almond meal, eggs, baking powder, bicarb and sugar. Pulse until smooth. If you have a small blender you might have to do this in 2 batches.
Grease and line a round cake tin. Pour the cake batter into the pan and bake for 40-45 minutes or until a skewer inserted in the centre of the cake comes out clean. Remove from the oven, and cool on a wire rack.
To make the orange syrup, boil the orange juice and sugar in a small pot over medium high heat for 10-15 minutes or until reduced by half and you have a syrup-like consistency. Set aside to cool.
For the icing, whisk the cream cheese and creme fraiche until smooth and you have a slightly stiff consistency. Refrigerate until ready to use.
When the cake has completely cooled, ice the top of the cake with the creme fraiche icing, drizzle with the orange syrup and top with chopped pistachios.