Line a large baking sheet with parchment paper or a silicon mat.
Measure out the dried cranberries, pistachios, and coconut, if using. Set aside.
Fill one large pot with water and place a smaller pot or bowl inside creating a double boiler. Bring water in the larger pot to a boil then reduce to lowest heat. Ensure no water is able to escape into the smaller pot or it will cause your chocolate to seize and separate!
Break the dark chocolate into bite-sized pieces and add it to the smaller pot. Stir the chocolate continuously until melted. Remove from heat immediately once melted. If you allow it to overheat, this will also cause the chocolate to seize and separate!
Pour the melted chocolate onto the parchment lined baking sheet. Use a spatula to smooth the melted chocolate into an even layer, about 1/4 inch thick. Quickly sprinkle the dried cranberries, pistachios, and coconut flakes over the chocolate. Using the back of a clean spoon, or clean hands, gently press the toppings into the chocolate.
Place the baking sheet in the fridge to chill for at least 20 minutes, or until firm.
Once the chocolate is solid, break or cut it into pieces. Enjoy!