Whisk together the sugar, eggs and oil until thick and creamy - about 15 to 20 minutes.
Measure 200mls yoghurt into a jug and stir in the maple syrup, vanilla essence and lime juice.
Add this to the egg mixture and fold in the grated parsnip.
Beat in the dry ingredients until well combined.
Pour the mixture into a 9 inch/ 23cm deep push-up or spring-form pan.
Bake at 350 deg F/180 C/gas mark 4 for 1 and a half hours, testing after 1 hour.
To make the frosting:
Cream the cheese and butter together.
Sift the icing sugar and beat it into the mixture.
Gently fold in the ginger.
Frost the cake once it is completely cool.