Pre-heat your oven to 160C Fan/180C/350F/Gas Mark 4, and grease and line two 8" cake tins (that are at least 2" deep)
In a large mixing bowl, stir together the self raising flour, light brown sugar, cinnamon, ground ginger, mixed spice, baking powder and bicarbonate of soda
In another bowl, or large mixing jug, whisk together the vegetable oil, maple syrup, vanilla extract and eggs
Pour the oil/egg mixture into the mixing bowl with the flour in it, whisk everything together
Then mix in the grated parsnips and the chopped pecans
Divide the mixture between the tins, use scales for accuracy
Bake them for 35-40 minutes or until a skewer inserted in the middle comes out clean. Leave them to fully cool either in the tins or remove from the tin and place on cooling racks
To make the filling use an electric mixer to whisk the mascarpone with the maple syrup until smooth
If the cakes have domed on top, level them off with a cake leveller or a serrated knife
Put one of the sponges on your plate or cake stand and spread the sweentened mascarpone over it
Put the other half of the cake on top and finish with a sprinkling of icing sugar
Leftovers will keep in an airtight container in the fridge for 3 days
Notes
Make sure all your ingredients for the cake (particularly the eggs) are at room temperature before you start baking.
You can use a different type of oil besides vegetable oil. I'd recommend one that doesn't have a strong flavour, canola and sunflower oil would both work well.
Mixed spice is a British spice blend containing cinnamon, coriander seed, nutmeg, clove, pimento and ginger. If you can't get hold of it, you can use a mix of ginger, nutmeg and cinnamon, or use a Pumpkin Spice mix instead.
I really recommend using light brown soft sugar if you can, as it gives the cake a lovely caramel flavour. But if you can't get hold of it, you can use golden caster sugar or regular caster sugar (superfine sugar) instead.
If you like, you can swap the pecans for walnuts, or another nut of your choice. You can also omit the pecans to make this a nut free cake.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50) .
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.