Line a small loaf pan or container with parchment paper, leaving some paper over the sides for easy removal.
Place the honey in a small saucepan and warm it gently over low heat. Do not bring it to a boil.
Add the tahini, vanilla, and salt to a mixing bowl.
Slowly pour the warm honey into the tahini while stirring continuously until the mixture becomes thick and well combined.
Fold in the chopped nuts and cinnamon if using.
Transfer the mixture to the prepared pan and press it down firmly with a spatula or the back of a spoon.
Refrigerate for at least 2–3 hours, or until firm enough to slice.
Remove the halva from the pan, cut it into small squares, and serve.