Heat the oven to 220C/425F/Gas 7.
Beat the egg yolks and sugar in a bowl until pale and thick.
Meanwhile, heat the cream and vanilla pod in a pan until almost boiling. Remove from the heat and pour it over the egg mixture, whisking to combine. Return the mixture to the pan and stir until thickened.
Slice the clootie dumpling and arrange in a gratin dish. Pour the custard over and then bake in the oven for 10-12 minutes until golden and set.
Remove from the oven and serve.