This could happen with almond milk, and some pudding boxes even state not to use a certain type of milk, such as soy milk. This especially true if you're using a standard instant boxed pudding.

Whisk the cornflour with a little of the almond milk to a smooth paste. Set aside. In a saucepan, heat the remaining almond milk with the sugar, vanilla essence, rosewater and cardamom pods over a ...