Preheat the oven to 190C/375F/Gas 5.
Grease and line two 23cm/9in cake tins.
Beat the sugar and butter together in a bowl until pale and creamy, then gradually add the eggs, alternating with a tablespoon of flour. Gently fold in the rest of the flour and vanilla extract, then divide equally between the two cake tins.
Bake in the oven for 25-30 minutes, or until cooked through and lightly golden. Remove from the oven and turn out onto a wire rack to cool.
When cool, spread one cake with jam and whipped double cream, then place the other cake on top. Dust with icing sugar and serve in slices.