I just wanted to state, since someone asked a question “What is custard powder?” I did not realize that US citizens don’t get such a thing! LOL! I did a Google search but could find no real equivalent to custard powder, although some sites did mention pudding mix. Custard powder is basically corn flour, salt and flavoring with a bit of tartrazine thrown in for good measure (LOL!) I checked the ingredients. It has a sweet pudding flavor. I reckon you could use a pre-boxed pudding mix, just use the same amount. Check the box ingredients, it should contain corn flour. I hope this helps! It’s hard to say what products differ from country to country!