Preheat the oven to 180C/160C Fan/Gas 4. Grease and line two 20cm/8in sandwich tins. Use a piece of baking paper to rub a little butter around the inside of the tins until the sides and base are lightly coated, then line the bottom with a circle of baking paper.
Break the eggs into a large mixing bowl, then add the sugar and mix together well. Next, gently fold in the flour and mix together until well combined. The finished mixture should fall off a spoon easily.
Divide the mixture evenly between the tins. Use a spatula to remove all of the mixture from the bowl and gently smooth the surface of the cakes.
Bake the cakes on the middle shelf of the oven for 25 minutes. Check them after 20 minutes. The cakes are done when they’re golden-brown and coming away from the edge of the tins. Press them gently to check that they are springy to the touch. Set aside to cool in their tins for 5 minutes. Run a palette or rounded butter knife around the inside edge of the tins and carefully turn the cakes out onto a cooling rack.
To assemble the cake, place one cake upside down onto a plate and spread it with plenty of jam, then spread over the whipped cream. Top with the second cake, top-side up. Sprinkle over the icing sugar.