150g/5oz strawberry jam
400g/14oz plain flour
2 tsp baking powder
1 tsp bicarbonate of soda
400g/14oz golden caster sugar
pinch cinnamon
85g/3oz cocoa powder
陆 tsp salt
3 tbsp sunflower oil
1 tsp vanilla extract
chocolate buttons, to decorate
250驳/8陆辞锄 butter, plus extra for greasing
150ml/5fl oz double cream, whipped until stiff peaks form when the whisk is removed
3 free-range eggs, beaten
220ml/8fl oz flat cola