Make the syrup by splitting the vanilla bean in half and placing in a small pot with the sugar, water, spices and salt
Bring to a gentle simmer and simmer for 5 minutes and remove from the heat
Add the brandy and let the syrup infuse for 30 minutes
Strain the syrup and set aside
Preheat the oven to 190 degrees C
Grease a 24cm springform cake tin and line the base with baking paper
Place the oranges in a small pot and and cover with water and gently simmer for 75 minutes
Remove the oranges and cool for 30 minutes
Roughly chop the oranges with the peel on, remove the pips and blend in a food processor to a smooth puree
Whisk the eggs and sugar, add the extract and beat well
Add the almonds, polenta, baking powder, orange puree, zest and olive oil and mix well
Pour the mixture into the baking tin and bake for about 45 minutes until light golden and firm to the touch
Leave to cool in the tin for 10 minutes, turn out on a wire rack and let the cake cool completely
Transfer the cake to a plate and use a toothpick to prick the cake all over
Spoon spoonfuls of the syrup over the cake, allowing it to soak through the cake before adding more
Continue until all the syrup is finished