Heat oven to 350°F.
In a small bowl, whisk flour,cocoa powder, pumpkin pie spice, ginger, baking soda and white pepper.
On a well-floured surface, knead cookie dough and flour mixture. Add 1 tablespoon milk and continue to knead until smooth.
Using level tablespoons of dough, form into 1-inch disks and coat in the coarse sugar. Place 2-inches apart on ungreased baking sheets.
Bake at 350°F for 12 minutes. Let cool on baking sheet for 2 minutes. Remove to wire rack to cool.