Preheat the oven to 190C/375F/Gas 5. Lightly grease and flour two 20cm/8in loose-bottomed sponge tins, at least 4cm/1½in deep, and line the bases with greaseproof paper.
To make the jam, tip the strawberries, sugar and lemon juice into a large pan and stir over a moderate heat for 2-3 minutes or until the sugar has dissolved. Turn up the heat and boil for five minutes – this is an “instant jam” so you don’t have to check for setting point. Remove from the heat, pour into a tray and set aside to cool. The jam will keep in the fridge for up to a week.
Beat together the butter, sugar and a pinch of salt until well creamed. Gently whisk the eggs in a small bowl and then add them, a little at a time, to the creamed butter mixture. Fold in the flour and divide the mixture between the two lined tins.
Bake for 25-30 minutes or until well-risen and golden-brown on top. Remove from the oven and turn the cakes out onto a wire cooling rack. Peel off the greaseproof paper and leave to cool completely.
Meanwhile, make the strawberry decorations. Heat the sugar in a small pan over a moderate heat until it starts to turn a pale caramel colour. Remove from the heat and carefully dip the strawberries into the caramel. Set aside on a non-stick mat to cool.
To serve, place one of the sponges on a plate or cake stand and spread with the cream and strawberry jam. Place the second sponge on top and dust with icing sugar. Finish by arranging the caramel-dipped strawberries on top of the cake.