Instant vanilla pudding mix is perhaps the most common substitute for custard powder. The amount of pudding mix used should equal the amount of custard powder indicated in a recipe. Mixtures that contain ingredients such as cornstarch and inert sugar may also serve as custard powder replacements.
Custard powder is a product more common in Great Britain than in America. It is typically mixed with sugar and milk to create a custard sauce. The product contains ingredients found in many of its substitute mixtures, such as cornstarch and vanilla flavoring. Custard powder was originally invented as an alternative to eggs for thickening custard.