Pour the chocolate custard on top. Cover and chill for 2–3 hours, or overnight, until the custard is softly set. Whip the cream in a bowl using an electric whisk, or by hand, until just thick ...
Pop the chocolate hazelnut spread into a bowl with the milk and heat in the microwave in 10-second bursts until the mixture is runny and viscous, but not steaming hot. This should not take more ...