Preheat oven to 350°F. Spray a 9" x 9" square baking pan with non-stick cooking spray. Then line with parchment paper, letting it extend over two sides (so you can easily pull the brownies out when they were done). Set aside.
Prepare the brownie mix according to package instructions. Pour brownie batter into prepared pan. Bake as directed. Let cool.
Place the coconut milk (or heavy cream) in a medium, microwaveable bowl. Microwave on high until it just begins to bubble, about 30-40 seconds. Stir in chocolate chips until melted and smooth. Let the ganache stand until cooled, about 30 minutes. Pour the frosting over the cooled brownies.
For the candy ghosts, melt candy melts in a microwave safe bowl according to package instructions. Scoop teaspoon sized dollops onto parchment lined cookie sheet, then use an offset spatula or back of a spoon to smooth out into a ghost shape. Put in refrigerator for 15 minutes or until set. Decorate with black frosting, creating eyes and mouth. Place on brownies and serve. You can cut brownies into 8 larger squares or 16 smaller squares.