This question already has an answer here:
... Fiction writers (eye roll)
To be burned at the stake
If we can't come up with a verb, perhaps a corresponding noun or adjective would suffice.
15th century historical fiction, so modern terms such as marshmallowed wouldn't really help.
Here is my sample:
You, the accused, have been found guilty of practicing Judaism as a Christian. This heresy against our Lord Savior carries the penalty of ____(noun).
[C]onvicted of heresy, you are to be ____(verb).