I originally presented this content at ParDreamin 2020. It explains all the fantastic things you can do with the new handlebar merge language feature released in Pardot in 2019.
The session recording below is re-recorded and expanded to include instructions for how to enable prospect resubscribe, since that feature was only enabled on about a third of the orgs represented by session participants. I also include two riffs on the alternate custom redirect example, and more explanations since I was not constrained by the session time.
The Pardot NPS Survey example mentioned in the session is fully fleshed out in this post and video.
You may download the presentation and the Legacy/HML cross reference spreadsheet here.