Preheat the oven to 180°C.
Grease and line two 20cm sandwich tins with baking paper.
Add eggs, sugar, flour, baking powder, and baking spread into a large bowl.
Mix ingredients with an electric hand mixer until well combined and a soft dropping consistency is reached.
Divide the mixture evenly between the two tins and smooth the surfaces with a spatula.
Bake on the middle shelf for 25 minutes without opening the door.
Cool cakes in tins for five minutes before transferring to a wire rack.
Allow the cakes to cool completely.
Spread jam and optional whipped cream onto the bottom of one cake.
Place the second cake on top and sprinkle with caster sugar.