2 lemons, 1 cut into rings with peel left on and 1 zested and juiced
6 tbsp golden syrup
1 tsp baking powder
60g/2¼oz soft light brown sugar
175g/6oz caster sugar
1 tbsp cornflour
175g/6oz self-raising flour
1 vanilla pod, split, seeds removed and pod reserved
175g/6oz salted butter, softened, plus extra for greasing
550ml/19fl oz double cream
3 free-range eggs, beaten
6 free-range egg yolks
2 tbsp full-fat milk