Grease 2 x 20 cm (8 inch) loose-bottomed, round cake tins lightly with margarine, and line the bases of the tins with nonstick baking paper. Cream the margarine and sugar in a food processor with the vanilla essence until smooth.
Sift the flour and baking powder over the creamed mixture, add the eggs, ground rice and yogurt and whiz together until creamy. Fold the strawberries into the mixture.
Divide the mixture between the prepared tins and bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 35–40 minutes until risen, golden and springy to the touch. Allow to cool in the tins for 10 minutes before removing to a wire rack to cool completely. Remove the baking paper.
Whisk the cream until soft peaks form. Cut the top off one of the cakes to level it, then spread with the jam and then half of the cream to the edges. Scatter with two-thirds of the strawberries. Place the other cake on top and spread with the remaining cream. Scatter with the remaining strawberries or form them into your child's initials. Add candles.