1 orange, skin on
100g/3½oz thick-cut orange marmalade
½ tsp bicarbonate of soda
100g/3½oz caster sugar
125g/4½oz caster sugar
175g/6oz self-raising flour
1 vanilla pod, seeds removed (keep the pod)
100g/3½oz unsalted butter, softened
250ml/9fl oz double cream
2 free-range eggs
5 free-range egg yolks
250ml/9fl oz full-fat milk
2 tbsp Bourbon whiskey