POSITION racks in upper and lower third of oven. Preheat to 350°F Lightly grease or paper-line two baking sheets with parchment paper.
MELT morsels in microwave-safe bowl on MEDIUM-HIGH (70%) power for 45 seconds; STIR. Morsels may retain some of their original shape. Microwave at additional 10- to 15-second intervals, stirring just until morsels are melted. Set aside.
COMBINE sugar, cinnamon and chili powder in small bowl. Beat egg whites and cream of tartar in small mixer bowl on high speed until soft peaks form when beaters are lifted. Beating on high speed, gradually add sugar mixture and vanilla until whites are glossy and stiff peaks form. Gently fold in nuts and melted chocolate until mixture is just uniform. Spoon mixture into gallon-size food storage bag with with 1/2-inch snipped from corner of bag. Pipe mixture into 1 1/2-inch circles about 2 inches apart onto prepared baking sheet.
BAKE for 7 to 8 minutes or until cookies are shiny and cracked. They should be firm on the outside and gooey on the inside. Immediately remove cookies to wire rack or slide parchment to wire racks to cool completely. Store cookies in airtight container at room temperature. Cookies are best eaten the day they are baked but will last a day or two.