Heat oven to 350°F.

In large bowl, break up cookie dough. Add cocoa and flour; stir with spoon or hands until well blended.

Shape into 28 (1-inch) balls. Roll each ball in 1/4 cup of the powdered sugar (reserve remaining powdered sugar). Place balls 2 inches apart on ungreased cookie sheets.

Bake 9 to 12 minutes or until tops are cracked and edges are set. Cool 2 minutes; remove from cookie sheet to cooling racks. Dip tops of each cookie in remaining 2 tablespoons powdered sugar. Cool completely, about 20 minutes.