Preheat the oven to 180°C (350°F/Gas 4). Lightly grease two 22cm (8½inch) sandwich tins or round cake tins and line the bases with baking paper. Dust the tins with a little flour, shaking off any excess.
Sift the flours together three times onto a piece of baking paper. Beat the eggs in a large bowl using electric beaters for 7 minutes, or until thick and pale. Gradually add the sugar to the egg, beating thoroughly after each addition. Using a large metal spoon, quickly and gently fold in the sifted flour and boiling water.
Spread the mixture evenly into the tins and bake for 25 minutes, or until the sponges are lightly golden and shrink slightly from the sides of the tins. Leave the sponges in their tins for 5 minutes, then turn out onto a wire rack to cool.
Spread jam over one of the sponges. Whip the cream in a small bowl until stiff peaks form, then spoon into a piping (icing) bag and pipe rosettes over the jam. Place the other sponge on top. Dust with icing sugar before serving.