Preheat oven to 180˚C bake. Grease and line an 18cm square baking tin.
Place all cake ingredients together in a food processor, in the order listed above, and process for 15 seconds.
Pour mixture into prepared tin and bake for 20-25 minutes, until a skewer inserted into the centre comes out clean.
For topping - mix the lemon juice, Chelsea White Sugar and boiling water together to form a runny syrup. Spoon topping onto cake while hot. Leave to cool in tin.