CAKE:
170 g (6 oz) butter (at room temperature)
140 g (5 oz) Chelsea Caster Sugar
3 eggs
140 g (5 oz) self-raising flour
1 tsp vanilla extract
4 tbsp raspberry jam

ICING:
80 g (3 oz) butter, at room temperature
150 g (5 1/2 oz) Chelsea Berry Flavoured Icing (sifted)
1-2 tbsp milk

Preheat the oven to 180°C (350 Fahrenheit / Gas mark 4). Grease a 20-cm (8-in) round cake tin, and line the bottom with greaseproof paper.
Beat together the butter and Chelsea Caster Sugar until pale and creamy, then beat in the eggs one at a time.
Sift the flour over the top, then fold in. Divide the mixture between two bowls.
Stir the vanilla extract into one; stir the raspberry jam into the other bowl and fold in. Place both batters in the cake tin and use a fork to mix the batter by dragging it to make a marbled-like effect.
Bake for about 45 minutes until risen and golden.
Transfer to a wire rack and leave to cool completely.

Icing
Beat together the butter, Chelsea Berry Flavoured Icing and 1-2 tablespoons of the milk until smooth and creamy, then spread the icing over the cake.