There are also good substitutes for cornstarch, such as tapioca starch, potato starch, and arrowroot powder. However, note that these substitutes can change your biscuits' texture. For example ...

After about 10 minutes of gentle simmering, mix the arrowroot in a small bowl with ... the cream mixture into the trifle bowl.) For the biscuit layer, whisk the jam, Marsala (or sherry) and ...