Preheat the oven to 325 degrees. Toast the cashews on a baking sheet in the preheated oven for 20 minutes, until uniformly golden brown. Cool the nuts to room temperature. Toast the coconut on a baking sheet in the preheated oven for 10 minutes, until lightly golden around the edges. Cool the coconut to room temperature. Heat 1-inch of water in the bottom half of a double boiler over medium heat. Place the semisweet chocolate in the top half of the double boiler. Use a rubber spatula to stir the chocolate until completely melted and smooth, about 5 to 6 minutes. transfer the melted chocolate to a 4-quart bowl. Add the cashews and coconut. Use a rubber spatula to stir until the cashews and coconut are completely coated with chocolate.
Immediately portion the mixture by heaping tablespoons (approximately 1 1/2 ounces) for each cluster, onto waxed paper. Allow the clusters to harden at room temperature for 1 hour, then refrigerate for 30 minutes, until firm enough to handle. Store the clusters in a tightly sealed plastic container in the refrigerator until ready to serve.