For the custard add the egg yolks, sugar and cornflour to a bowl. Whisk until well combined. In a saucepan, heat the cream with the vanilla pod. Once the cream has come to the boil, slowly pour over the egg yolk mixture whisking all the time. Pour the mixture back into the saucepan and cook gently until it thickens and coats the back of a spoon. Pass through a sieve before serving with the jam roly poly and a sprinkling of raspberries.