To make the cake: preheat the oven to 160°C/320°F/gas 2½. Generously grease a 20cm (8 inch) springform tin and line it with parchment paper.
In a large bowl beat the butter and sugar until light and creamy. Then beat in the eggs one at a time and stir in the vanilla essence.
In a small bowl mix the ground almonds, polenta, orange zest and baking powder, then stir this into the cake mix.
Pour the mixture into the prepared cake tin and bake for 40 to 50 minutes, or until it’s light brown. Allow the cake to cool for 10 mins and then turn it out onto a plate.
To make the syrup: put the orange juice, Seville Orange Marmalade and sugar into a saucepan. Simmer over a medium-low heat for about 10 minutes, or until reduced and thickened slightly. Set aside to cool.
Finally, prick the cake all over with a skewer, then brush generously with the syrup. Serve if you fancy with crème fraîche or yoghurt and an extra drizzle of syrup.