1. In food proceessor, pulse flour, cocoa, and salt. Add all butter and process until sandy, about 3 minutes. Add all powdered sugar, milk, and vanilla, and process until a firm dough forms. 2. Transfer dough to 2 sheets of plastic wrap and form into two 7" logs, about 1 1/2" thick. Wrap in plastic and refrigerate until very firm, at least 4 hours or overnight. 3. Preheat oven to 350 degrees. Position racks in upper and lower thirds of oven. 4. Line 2 large baking sheets with parchment paper. 5. Beat egg white in a small bowl. 6. Sprinkle granulated sugar in a 7" square on a sheet of wax paper. 7. Brush the cookie logs with the egg white and roll them in the sugar, pressing to help sugar adhere. Cut logs into 1/4" slices and place on baking sheets about 1/2" apart. Bake cookies for about 20 minutes, until just firm to touch; shift the sheets from top to bottom and front to back of oven hafway through for eveb baking. Transfer baking sheets to racks to cool. Store cookies in airtight container for up to 2 weeks. ---------------------------------------------------------------------------
Nutrition
Ingredients
