Add all ingredients for the shortbread to a stand mixer or a mixing bowl. Beat until a dough forms. Note: it's okay if the mixture is crumbly - this is normal.
Turn dough out onto a large piece of plastic wrap and use your hands to form it into a large ball. Work the dough into a cylinder. I use the plastic wrap to help keep the cylinder intact while shaping it.
Transfer cylinder of dough to the freezer and freeze at least 2 hours. When you're ready to bake, allow the dough to thaw so that it's easy to cut but is still chilled.
Preheat the oven to 350 degrees F and line a large baking sheet with parchment paper.
Slice dough into 1/4-inch to 1/2-inch rounds using a sharp knife. Place dough rounds on the parchment-lined baking sheet.
Bake 10 to 15 minutes, or until cookies are golden-brown around the edges. Remove form the oven and allow cookies to sit 30 minutes (during this time, you can prepare the chocolate shell). Use a spatula to transfer cookies to a plate or wire rack.
Make the Chocolate Shell:
Add all ingredients for the chocolate shell to a small saucepan and heat over medium-low, whisking constantly. Heat and whisk just until all ingredients are combined and a smooth, creamy chocolate sauce has formed.
Once the shortbread cookies have cooled completely, drizzle them with the chocolate shell mixture. I do this by holding the shortbread over the saucepan (to minimize mess) and using a spoon to drizzle and fully coat the surface of the cookie.
Transfer cookies to a wire rack to allow the chocolate to harden. Once the chocolate is hard, you're ready to serve!