125 g (4 oz) unsalted butter, softened, plus extra for greasing
125 g (4 oz) caster sugar, plus extra for sprinkling
125 g (4 oz) self-raising flour, sifted
1 teaspoon baking powder
1 teaspoon ground ginger
2 large eggs, lightly beaten
1 tablespoon milk
4 tablespoons blackcurrant jam
Grease 2 x 20 cm (8 inch) round cake tins and line with nonstick baking paper.
Place all of the ingredients except the jam in a large bowl and beat together with a hand-held electric whisk until pale and creamy.
Divide the mixture between the prepared tins and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 15–18 minutes until risen and firm to the touch. Turn the cakes out of the tins on to wire racks, peel away the lining paper and leave to cool.
Spread 1 cooled cake thickly with the blackcurrant jam and top with the second. Sprinkle with caster sugar and serve cut into wedges.