Preheat the oven to 160℃, grease and line a 20 cm springform tin with baking paper.
Beat the softened butter and demerara sugar together until it's light and creamy. Don't worry if it looks grainy, the sugar will melt when its cooking.
Beat in the eggs in slowly, one at a time. Then add the vanilla bean paste.
Add the ground almonds, polenta and baking powder. Mix slowly until it is all combined.
Then add the zest of four oranges, the juice of one and the orange extract. Mix until it is well combined.
Pour the cake mix into the springform tin.
Bake for 45 minutes. It should be golden on top and the sides should start coming away from the sides.
Leave to cool in the tin for 10 minutes before transferring to a cooling rack.
Meanwhile, make the glaze. Add the Orange juice, orange extract and golden caster sugar into a saucepan. bring to the boil, then turn down to a medium heat and simmer for five minutes.
Allow it to cool slightly before pouring it all over the cake.
Serve with a dollop of creme fraiche or yoghurt.
