1/2 cup Dutch-process unsweetened cocoa powder
1/8 teaspoon salt
1 cup (2 sticks) unsalted butter, at room temperature
1 cup confectioners' sugar
1 1/2 teaspoons vanilla extract
3/4 cup walnuts, toasted and coarsely chopped
3 tablespoons granulated sugar
Combine the flour, cocoa, and salt and toss well just to mix them.
In the bowl of an electric mixer, cream the butter at medium speed for 3 minutes. Add the confectioners' sugar and beat at low speed for 1 minute. Mix in the vanilla. Add the flour mixture and mix to form a stiff dough.
Remove the mixer from the stand and stir in the nuts. Divide the dough in half.
Place each portion of dough on a piece of plastic wrap. Form each piece into a log 10 inches long and 1 1/2 inches wide, wrapping the plastic around it and folding the ends under the logs. Refrigerate overnight.
Set the oven at 325 degrees. Have on hand two baking sheets. Line them with parchment paper.
Slice the dough into 1/4-inch slices and place them on the prepared sheets. Sprinkle with the granulated sugar.
Bake the cookies in the hot oven for 18 to 20 minutes or until they are set and crack slightly on top. Halfway through baking, rotate the sheets and switch their positions on the racks.
Remove the cookies from the oven. Use a wide metal spatula to transfer them to cooling racks. Let them cool completely. Store in an airtight container.
Makes about 4 Dozen