Directions

1. Sift together flour, cocoa, salt, espresso powder, and cinnamon into a large bowl; set aside. Put butter and sugar into the bowl of an electric mixer fitted with the paddle; mix on medium until pale and fluffy. Mix in egg and vanilla. Reduce speed to low. Add flour mixture; mix until just combined. Stir in cocoa nibs.
2. Turn out dough onto a lightly floured surface; roll into a 2-inch-diameter log. Wrap in parchment; transfer to a paper towel tube to hold shape. Refrigerate until firm, at least 1 hour or up to overnight.
3. Preheat oven to 350 degrees. Unwrap log, and let soften slightly at room temperature, about 5 minutes. Brush with water, then roll in sanding sugar. Cut log into 1/4-inchthick rounds. Space 1 inch apart on baking sheets lined with parchment paper.
4. Bake until centers are set, about 10 minutes. Transfer to wire racks; cool completely. Store in airtight containers at room temperature up to 2 days.