Preheat oven to 350 degrees F. Line a baking sheet with parchment paper or Silpat baking mat or parchment paper. Set aside.
In a medium bowl, whisk together flour, baking soda, salt, cocoa, cayenne pepper, and cinnamon. Set aside.
With a mixer, cream butter and sugars together until smooth. Add in egg and vanilla and mix until combined.
Gradually add flour mixture and beat until just combined. Stir in the chili chocolate chunks. Scoop the dough into rounded tablespoons and place on prepared baking sheet, about 2 inches apart. Bake cookies for 8-10 minutes, or until cookies are set, but still soft in the center. Don't overbake. Remove from oven and let sit on baking sheet for 3 minutes. Move to a cooling rack and cool completely.
Note-store cookies in an airtight container for up to 4 days. You will need 2 (3.5 oz) Lindt EXCELLENCE Chili bars for this recipe. You won't use all of the second bar for the cookies, but you can save the rest for eating!