Pre-heat the oven to 180ºc and line a 30cm cake pan with baking paper.
Mix together all the dry ingredients.
Cream together the butter and sugar until light and fluffy.
Add the eggs and dry ingredients alternatively until all the ingredients are well incorporated.
Add the lemon juice and zest and mix well.
Transfer the batter to the prepared cake pan and place in the oven.
Bake the cake for 40-50 minutes or until a skewer inserted comes out clean. Don't be alarmed if the cake has sunk in the middle, that's completely normal. Because this cake is so dense and moist and because of the lack of flour, this will most likely happen.
Remove the cake from the oven and allow to cool completely before removing from the pan.
To make the syrup, combine the ingredients and mix until the sugar has dissolved.
Pour over the cake then serve with a dollop of mascarpone.