Preheat your oven to 150°C (300°F). Line a large baking sheet with parchment paper or a silicone baking mat. This prevents the nuts from sticking and makes cleanup easier.

In a large bowl, whisk together the egg whites and vanilla extract until slightly frothy. This creates a base to help the coating adhere to the nuts.

In a separate medium bowl, combine the unsweetened cocoa powder, granulated sugar, chili powder, cinnamon, salt, and cayenne pepper. Whisk these dry ingredients together thoroughly to ensure even distribution of spices and cocoa.

Add the mixed nuts to the bowl with the egg white mixture. Toss them gently until all the nuts are evenly coated. Ensure each nut has a thin layer of the egg white mixture.

Pour the dry cocoa and spice mixture over the coated nuts. Toss again until every nut is thoroughly coated with the cocoa-spice blend. Make sure there are no clumps of spice mixture.

Spread the coated nuts in a single layer on the prepared baking sheet. It is crucial to have them in a single layer to ensure even roasting and prevent them from steaming instead of toasting.

Bake in the preheated oven for 25-30 minutes, stirring the nuts every 10 minutes. Stirring is essential to prevent burning and to ensure all sides of the nuts are toasted and the coating is dried evenly. They should smell fragrant and the coating should look dry.

Once baked, remove the baking sheet from the oven. Allow the nuts to cool completely on the baking sheet. As they cool, the coating will become crispier and less sticky. Resist the urge to try them while hot, as the flavor develops as they cool.

Once completely cooled, break apart any clumps of nuts. Store the Cocoa Chili Spiced Nuts in an airtight container at room temperature for up to 2 weeks.