Beat all of the cake ingredients in a mixing bowl or a food processor until smooth.
Spoon the cake mixture evenly into 2 greased and base-lined 18 cm (7 inch) sandwich tins and spread the surfaces level. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 20 minutes until well risen, the cake is golden brown and springs back when gently pressed with a fingertip.
Leave to cool in the tin for 5 minutes then loosen the edges, turn out on to a wire rack and peel off the lining paper. Leave to cool.
Transfer one of the cakes to a serving plate and spread with the lemon curd. Spoon the whipped cream on top then cover with the remaining cake. Dust the top of the cake lightly with sifted icing sugar. This is best eaten on the day it is made.