Source: Chocolate Desserts by Pierre Herme and Dorie Greenspan

Makes about 30 cookies.

These delicate icebox cookies are a delectable way to savor the essence of chocolate flavors. To make the edges crisp, roll the cookies in crystallized sugar before baking.

2 3/4 cups all-purpose flour
1/3 cup natural unsweetened cocoa
Pinch of ground cinnamon
Pinch of salt
1 1/4 cups (2 1/2 sticks) unsalted butter, at room temperature *
1/2 cups plus 2 tablespoons granulated sugar
1/4 teaspoon vanilla extract
1 egg yolk
Granulated sugar for coating

* Use real butter or stick margarine. Do not substitute reduced-fat spreads; their higher water content often yields less-satisfactory results.

Sift the flour, cocoa, cinnamon and salt together and keep close at hand. Place the butter in a mixer fitted with the paddle and beat on medium speed to soften it. Gradually add the sugar and vanilla extract and continue to beat, scraping down the sides of the bowl as needed, until the mixture is smooth and creamy but not airy.

Reduce the mixer speed to low and add the flour mixture, blending only until the ingredients are just combined - no more. Alternatively, you can remove the bowl from the mixer and stir the flour into the dough with a rubber spatula. The point is to mix the dough as gently as possible - this light touch is what will give the cookies their characteristic crumbly texture.

As soon as the last of the flour is no longer visible, divide the dough in half, shape each half into a ball, wrap the balls in plastic and chill for 30 minutes.

Working on a smooth surface, form each piece of dough into a log that's about 1 1/2 inches thick and 7 1/2 inches long. To get a solid log, one without that commonly found hole in the center; use the heel of your hand to gently flatten the dough, then flatten the dough lightly each time you fold it over on itself to make the log. Assured that the log is solid, you can roll it gently under your palms to smooth it out.

Wrap the logs in plastic and chill for 1 to 2 hours. (The dough can be made ahead, wrapped airtight, and stored in the freezer for up to 1 month.)

Position the racks to divide the oven into thirds and preheat the oven to 350 degrees F. Line 2 baking sheets with parchment paper and set them aside.

In a small bowl, whisk the egg yolk until it is smooth and liquid enough to use as a glaze; keep it close at hand. Spread some sugar out on a piece of wax paper.

Remove the logs of dough from the refrigerator; unwrap them and brush them very lightly with a small amount of the egg yolk. Roll the logs in the sugar, pressing gently on the sugar to get it to stick if necessary. Then, using a sharp slender knife, slice each log into cookies 1/2 inch thick.

Arrange the cookies on the baking sheets, leaving about an inch of space between each one, and bake for 15 to 18 minutes, rotating the pans front to back and top to bottom at the midway mark, until the cookies are just firm to the touch. Transfer the cookies to racks to cool to room temperature.

Unbaked logs of dough can be frozen for up to one month (before rolling them in sugar).

Baked cookies can be stored in an airtight container at room temperature for 3 to 5 days.