Preheat the oven to 160°C/320°F/gas 2½. Grease a 20cm springform tin, line the bottom and sides with greaseproof paper and grease again. Beat the butter and sugar in a large bowl until light and creamy – don’t worry if it looks gritty, as the sugar will dissolve when it’s cooked. Beat in the eggs, one by one, then stir in the vanilla essence. In a small bowl, combine the ground almonds, polenta, orange zest, orange blossom water and baking powder, then stir this into the cake mix. Pour the mixture into the tin and bake for 40 to 50 minutes, or until the surface is light brown and the cake is coming away slightly from the sides of the tin. Remove the tin from the oven, leave to cool for 10 minutes, then turn it out onto a plate. This cake will be quite fragile, so handle carefully as you remove it. To make the syrup, crush the cardamom pods, then put all of the ingredients in a saucepan. Simmer over a medium-low heat for about 10 minutes, or until reduced and thickened slightly. Set aside to cool. Prick the cake all over with a skewer, then brush generously with the syrup. Delicious served with a dollop of crème fraîche or yoghurt and an extra drizzle of syrup.