Preheat the oven to 350 degrees F.
Stir together all of the ingredients for the cookies in a mixing bowl until well combined. Form a ball (about 1-inch in diameter) out of the cookie dough, then press it into a disc and place on a large baking sheet. Repeat for remaining cookie dough. Bake 8 to 10 minutes, until cookies are slightly crispy on the edges. Remove from oven and cool 5 minutes before transferring to a wire rack to cool the rest of the way.
While the cookies are baking, prepare the chocolate mixture. Heat the ingredients on the stove top in a small saucepan until melted and smooth and well-combined, whisking constantly until all the clumps of chocolate are out. Remove from heat and immediately pour chocolate mixture into a small bowl. Allow mixture to cool to room temperature (you can refrigerate the chocolate to speed up the process). You want the chocolate to be thick enough to drizzle, but not super runny.
Once the cookies and the chocolate have cooled, use a spoon to drizzle the chocolate over half of each cookie. Sprinkle nuts, seeds, shredded coconut, cacao nibs, or toppings of choice over the chocolate while it's still melted. Allow cookies to dry. To speed up the process, you can refrigerate or freeze the cookies on a small cutting board until the chocolate has set up.