Whisk the eggs with the sugar and vanilla essence until thick and foamy and the whisk leaves a trail over the mixture. This is achieved most easily in a food mixer or using a hand-held electric beater. If you are making the cake by hand, using a balloon whisk or an egg beater, it is helpful to place the mixing bowl over a pan of simmering water while you whisk the mixture, then remove the bowl from the heat.
Place the flour in a large sieve and tap the side to give a dusting of flour over the top of the egg foam. Use a balloon whisk to fold in the flour gently. Repeat until all the flour has been incorporated.
Divide the mixture between the prepared cake tins. Bake in the preheated oven until the cakes are golden-brown and just starting to shrink from the tins. Cool the cakes in their tins for 2 minutes then turn out on to a wire rack and peel off the baking paper.
When the cakes are cold, spread the sieved jam in one layer. Whisk the cream until thick and glossy and spoon over the jam. Place the other cake on top and sprinkle with caster sugar. Set the cake in a cool place until ready to serve.