Mocha Slice Cookies
- 1 1/2 cups all-purpose flour, plus more for work surface
- 3/4 cup unsweetened Dutch-process cocoa powder
- 1/4 teaspoon salt
- 2 tablespoons instant espresso powder
- 1/4 teaspoon ground cinnamon
- 1 1/2 sticks unsalted butter, softened
- 1 cup granulated sugar
- 1 large egg
- 1 teaspoon pure vanilla extract
- 1/2 cup cocoa nibs
- Coarse sanding sugar
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.
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.
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.
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.