Preheat the oven to 180`c. Grease and flour a 30cm cake tin. Beat the butter and sugar together in a bowl until pale and fluffy. Add the almonds and mix together well. Add the eggs, one at a time, beating to combine well before adding the next egg. Add the vanilla essence and the fruit juices and zests and mix well. Add the polenta, salt and baking powder and stir well to combine. Spoon the cake mixture into the prepared tin. Cover with a piece of greaseproof paper and bake in the oven for 45-55 minutes, or until golden and firm. Remove from the oven and allow to cool completely. For the orange caramel sauce, place the butter and sugar into a pan over high heat and cook until they melt and begin to caramelize. Add the orange juice and stir well. Simmer for 4 minutes, until combined. To serve, slice a piece of cake and place onto a plate and drizzle over the orange caramel sauce.