The cake:
– Grease a 23cm loose-bottomed tin.
– And the butter and sugar to a large bowl, then add the orange rind and beat together until light and fluffy.
– Mix the polenta, flour, baking powder, ground almonds and the eggs into the butter and sugar and mix well until smooth once more.
– Stir in the 3 tbsp of orange juice.
– Spoon into the greased tin and sprinkle the blueberries over the top.
– Bake for about 35 minutes until a skewer comes out cleanly when inserted into the centre of the cake.
– Mix 50g of the remaining sugar with 3 tbsp of orange juice together in a pan and gently melt the sugar over heat while stirring.
– Skewer the top of the cake, then drizzle over the orange syrup and leave to cool.
When ready to serve, mix the mascarpone with the grated rind of half an orange rind and the rest of the sugar, then gradually mix in 2 tbsp of orange juice and the liqueur.
Top the cake with extra blueberries, and cut it into thin slices and serve with the mascarpone mix.