Preheat your oven to 300F. Line a baking sheet with parchment or silpat.
Place the aquafaba in a medium sized mixing bowl. Whisk it vigorously for 30 seconds, or until it's frothy.
Stir the sugar, cinnamon, chili powder, and salt into the beaten aquafaba. Continue mixing until you have a smooth, sticky, even mixture. Add the walnuts to the bowl and use a spatula to mix them with the aquafaba and sugar, until they're all evenly glazed.
Transfer the walnuts to your baking sheet and arrange them in a single layer.
Bake them for a total of 25-30 minutes, stirring on the sheet every 10 minutes. Each time you stir the nuts, be sure that you rearrange them in a single layer before returning them to the oven. When the nuts are browning and smell nutty, they're finished.
Allow the nuts to cool *completely* before breaking them apart. Store them at room temperature in an airtight container for up to 2 weeks.