Preheat oven to 180°C and spray and line a 20cm cake pan or 2 sandwich pans with parchment paper.
Boil 30ml water in a saucepan over medium heat. Then lower the heat to simmer.
In a glass bowl beat the eggs, then add the sugar and vanilla essence.
Place the glass bowl on top of saucepan to act as double boiler - making sure the water does not touch the glass bowl. Continuously stir egg/sugar mixture for 2 minutes.
Transfer the mixture to a stand mixer and add the whip attachment. Alternatively you can use a hand mixer if you don't have a stand mixer.
Whip mixture for 8 minutes until it doubles in size and it resembles a slight meringue colour.
Sift the flour and baking powder together. Use a big metal spoon and gently fold spoonfuls at a time into mixture. Then add melted butter and lemon zest. Continue to gently fold in using the figure of 8 motion. Make sure the flour is well incorporated but do not over mix.
Pour batter into the prepared cake pan/s and transfer to the preheated oven.
If you are baking one cake then bake for 30 minutes. If you divided the batter into 2 x sandwich pans, then bake for 20 minutes until the skewer comes out clean.
Remove the sponge cake from the cake pan/s immediately and place on a wire cooling rack to cool completely. Make sure it is away from any drafts to prevent sinking.
Top with fruit jam of your choice, whipped cream and berries or simply just dust with icing sugar. Serve and enjoy!
