In a medium bowl, whisk together the flour, cocoa powder, and salt. Set aside.
Using a stand mixer fitted with the paddle attachment or using a hand mixer, beat the butter on medium-high until fluffy, about 3 minutes. Add the sugar and beat until pale in color, about 2 minutes. Reduce the mixer to low and add the flour mixture, mixing until just short of combined. Add the cherries and walnuts and mix until just combined.
Lightly dust a work surface with cocoa powder. Transfer the dough to the work surface and form it into a 12-inch log, dusting with more cocoa powder as necessary. Cover with plastic wrap and chill for at least an hour.
Preheat the oven to 325°F. Prepare two parchment-lined baking sheets.
Cut the log into 1/3-inch slices, arranging the slices on the prepared baking sheets, about 1 inch apart. Bake, rotating and changing the position of the baking sheets as necessary, until firm, 17 to 20 minutes.
Transfer the baking sheets to a cooling rack to cool slightly, then transfer the cookies to the rack to cool completely.Copyright Jill Silverman Hough. All rights reserved. www.jillhough.com