The evening before you want to bake the cake put the two whole oranges it a pot with water and boil them for two hours. Take away from the heat and let them cool overnight out of the remaining water.
Preheat the oven on 180°C/375°F.
Next day cut the two oranges in halves and take out the pips (if they have any). Then put the whole oranges into the blender and blend until they are a smooth cream. Add the eggs, the honey and the vanilla, pulse again until all combined. Add now the dry ingredients and blend until it forms a smooth and even cream.
Line a cake pan of 8" with parchment paper and transfer the cake dough into the pan. Bake for around one hour or a toothpick in the middle of the cake come out clean.
Take the cake out of the oven, let it cool a little in the cake pan and then transfer the cake on a cooling rack.
Garnish with icing-sugar and/or thin orange slices.