Knock back your portion of pastry cream by mixing with a whisk until it’s no longer stiff. Store in the fridge until ready to serve and add the cream below. It will keep for 2 days (see storage below).
Whisk your whipping cream to medium peaks in a separate bowl and gradually fold into your pastry cream. Be careful not to knock the air out. Now you’re ready to serve!
Notes
Storage - The pastry cream will keep for a couple of days in the fridge, in a sealed container. I wouldn't recommend adding the whipped cream until ready to serve or else it won't hold as well.