Method

• Preheat the oven to 180 degrees
• Line the bottom of two 23cm round sandwich tins with baking paper
• Grease the sides of the tin with either an oil spray or melted butter and then dust with cornflour, gently tapping out any excess flour
• Triple sift together the cornflour, custard powder, cream of tartar and baking soda and set aside
• In the bowl of a stand mixer, place the egg whites, begin to whip them with the whisk attachment
• When they reach soft peak stage, start to add the sugar about ¼ at a time, whisking for a couple of minutes between each addition. Once the whites are glossy and all of the sugar has been added, add the yolks back in one at a time while the mixer is running
• Fold the dry ingredients in to the egg mixture, 1/3 at a time, taking care not to knock too much air out of the eggs
• Carefully divide the cake mix between the two cake tins evenly. Spread out across the top and place in the oven.
• Bake for approx 20 minutes. Check the sponges once they are puffed up and golden brown. Don’t be tempted to open the oven before around the 20 minute mark
• Once the sponges are golden and cooked, remove from the oven and leave to cool in the tin for 10 minutes before carefully turning out. 
• Allow to cool completely before filling.
• Whip some cream
• Spread one half of the cake with jam, followed by whipped cream and then top with the second sponge
• Finish by dusting with icing sugar and then enjoy!