Sift together the flour, one cup of sugar and the cocoa powder in a mixing bowl. Mix in the softened butter with an electric mixer or wooden spoon until smooth.
Transfer dough to an ungreased jelly roll pan or a 15-inch by 11-inch baking sheet. Press the cookie dough into the pan with you hands to form a smooth, even cookie.
Refrigerate the cookie dough in the pan for at least 10-minutes, then cut the dough lengthwise into four strips. Cut the strips crosswise into 32 rectangular sections. Cut each rectangular section on an angle to create 2 cookie wedges from each section.(Makes About 5-Dozen Cookies)
Bake for about 20-minutes, or until the top is dry. Remove the baking sheet to a wire rack and re-cut the cookies while still warm.
Let cool completely, sift the remaining confectioner’s sugar over the top of the cookies. Their flavor improves with time after being stored in an airtight container.