Chocolate Coins

Place chocolate chips and butter in a microwave-safe bowl and heat on high for 1 minute in microwave; stir to mix. Heat again until completely melted, 1 to 3 minutes, stirring. Set aside to cool, about 5 minutes. Meanwhile, in a medium bowl, whisk together flour, brown sugar, cocoa powder, and salt. Set aside. In the bowl of an electric mixer fitted with paddle attachment, beat together eggs and orange zest on low speed for 1 minute. With mixer still on low, pour in melted chocolate and mix for 1 minute. Scrape down sides of bowl as needed. Gradually add flour mixture and mix for 10 seconds. Turn dough out onto a lightly floured work surface and knead until flour has been incorporated and dough comes together, about 30 seconds. Divide in half; wrap one half with plastic wrap and set aside. Transfer unwrapped dough to a parchment-lined work surface. Flatten dough slightly with your hand, and then top with a second sheet of parchment. (Dust dough with flour if sticky.) Using a rolling pin, roll out dough between sheets of parchment to about 1/8-inch thickness; set aside. Remove plastic wrap from other dough half and repeat rolling process. Transfer dough, still sandwiched between parchment, to baking sheets and refrigerate until chilled, about 30 minutes. Preheat oven to 350 degrees F. Remove both dough halves from refrigerator and peel off all parchment. Using a 2 1/2-inch-wide scalloped-edged cookie cutter, cut cookies out of dough, rerolling scraps once. Place cookies on parchment-lined baking sheets, spacing 1 inch apart. Bake cookies until slightly firm, 10 to 12 minutes, rotating baking sheets halfway through. Transfer to a wire rack to cool.