Heat the Lactofree dairy drink with the vanilla pod until just boiling.
Mix the egg yolks together with the sugar and cornflour to get a smooth paste consistency.
Pour over the hot Lactofree whole dairy drink and stir well. Remove, wash and dry the vanilla pod (you can re-use this in another recipe!)
Strain the mixture back into a clean saucepan and, stirring constantly, cook gently until the custard thickens.