Dark Chocolate-Cherry Shortbreads

In a bowl, sift the flour with both cocoa powders and salt. In a stand mixer fitted with the paddle, beat the butter with the 1/4 cup of sugar at medium-high speed until fluffy. Beat in the zest. Beat in the flour mixture at low speed until the dough comes together. Add the cherries; beat until incorporated. Scrape the dough onto a work surface and pat it into a disk; roll it between 2 sheets of parchment paper to a 1/4-inch thickness and refrigerate on a baking sheet until firm, 1 hour. Preheat the oven to 350 ° and line a baking sheet with parchment paper. Peel off the top sheet of parchment from the dough. Using a 2-inch round cookie cutter, stamp out cookies. Arrange the cookies 1 inch apart on the baking sheet. Re-roll the scraps between parchment paper and stamp out more cookies; arrange on the baking sheet. Sprinkle with sugar. Bake the cookies in the middle of the oven for 13 minutes, until just set. Let cool for 5 minutes. Transfer to a rack to cool completely.