154g pack Oreo cookies, broken into chunks about the size of a large pea
Bring the milk and cream to a simmer in a pan. Meanwhile, whisk the egg yolks and sugar until combined. Pour the milk onto the eggs, stirring well. Pour this back into a cleaned-out saucepan and slowly heat through for about 10 mins, stirring all the time. Don’t allow the liquid to simmer. It should thicken as it heats up and is ready when it’s thick enough to coat the back of a wooden spoon.
Pour the hot custard mix over the chocolate in a bowl and allow it to melt. Add the Ovaltine and whisk until smooth.
Cool, then churn in an ice-cream machine. As it thickens, add the biscuits. Freeze. When ready to eat, serve with White chocolate sauce (below).