• Place butter in a large mixing bowl (or in the bowl of a stand mixer fitted with the paddle attachment) and use an electric mixer to beat on high-speed until well-creamed (at least 2 minutes on high speed).
  1 cup (226 g) unsalted butter
• With mixer on low-speed, gradually stir in powdered sugar, then cocoa powder.
  ¾ cup (95 g) powdered sugar, ¼ cup (25 g) Dutch-process cocoa powder
• Stir in vanilla extract and salt.
  1 teaspoon vanilla extract, ½ teaspoon table salt
• With mixer on low-speed, gradually stir in flour until completely combined (scrape the sides and bottom of the bowl periodically to ensure ingredients are well-combined).
  2 cups (250 g) all-purpose flour
• Turn out onto a clean surface and divide dough into two parts. Form each into a smooth, round disc (lightly flour your hands if the dough is too sticky to manage), wrap tightly in plastic wrap, and refrigerate for 30 minutes. Note that if your butter or kitchen are particularly warm, you may need to chill the dough longer, but in my kitchen I typically find that anything longer than 30 minutes makes the dough difficult to roll out and prone to cracking. If you do have to or want to chill your dough longer, don’t panic! Just let it sit (wrapped) on the counter at room temperature for 15-20 minutes or until it can be rolled out without cracking (dough should not be warm though).
• Preheat oven to 350F (175C) and line baking sheet with parchment paper. Set aside.

Rolling and Baking

• Once dough has chilled, remove from refrigerator and unwrap. Transfer to a lightly floured surface. Use a lightly floured rolling pin to roll cookies to ¼” (0.6cm) thick. Use cookie cutters to make close cuts in the dough and cut out as many shapes as possible. Once you’ve cut out all the shapes you can, regroup the dough and cut out even more shapes (the re-rolled cookies can sometimes look a bit funnier and be a bit more dry, so get as many cuts as you can the first time around!).
• Transfer cut-out cookies to prepared baking sheet, spacing cookies at least 1” (2.5cm) apart. Transfer to center rack of 350F (175C) preheated oven and bake for 12-14 minutes This will yield cookies that should have the perfect shortbread crispness to them once cooled.
• Allow cookies to cool on the baking sheet before removing to a rack to decorate with chocolate, if desired.

Chocolate (see note)

• Once cookies have cooled, decorate with chocolate if desired. Place chopped chocolate in a microwave-safe bowl and melt in 20 second intervals, stirring well in between, until completely melted. Transfer chocolate to a small bowl or mug and dip the cookies in chocolate (or drizzle the chocolate over the cookies). If desired, decorate with sprinkles while chocolate is still warm.
  6 oz (170 g) chopped baking chocolate, Sprinkles or nonpareils
• Allow chocolate to set before enjoying.