Instructions: Combine flour, cocoa, baking soda, and salt in a medium bowl and mix thoroughly with a whisk. Set aside. Combine sugars in a small bowl and mix well with your fingers, pressing out any lumps. (If lumps are stubborn, process in a food processor for a few seconds.) Set aside.

In a medium mixing bowl, beat butter and margarine until creamy. Add sugar mixture and peppermint extract. Beat on high speed for about 1 minute. Beat in egg white. On low speed, beat in flour mixture just until incorporated. Gather dough together with your hands and form it into a neat 9- to 10 inch log. Wrap in wax paper, twisting or folding the ends of the paper, without flattening ends of the log. Chill at least 45 minutes. (Cookies may be prepared to this point and refrigerated for up to three days or rewrapped in foil or plastic and frozen for up to three months.)

Place racks in upper and lower third of oven and preheat to 350 degrees. Line cookie sheets with parchment paper or aluminum foil. Use a sharp knife to slice rounds of chilled dough a scant 1/4 inch thick. Place 1 inch apart on cookie sheets. Bake for 12 to 14 minutes. Rotate baking sheets from top to bottom and front to back about halfway through. Cookies will puff and crackle on top, then begin to settle down slightly when done. Use a metal spatula to transfer cookies to a rack. Cool cookies completely before storing or stacking. Cookies may be stored, airtight, for up to two weeks or frozen for up to two months.

Makes
about 40 cookies.

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