In a microwave safe bowl, melt 200 gms – 7 oz. of dark.
Line a 20 cm – 8" x 8" square baking dish with baking paper, and spread your melted dark chocolate over the surface. Refrigerate until hard.
In another microwave safe bowl, heat 135 gms – 4 ¾ oz. of white chocolate, and spread it over your first layer of chocolate. Refrigerate again until the white chocolate has hardened.
Melt the remaining dark chocolate and white chocolate in two separate bowls.
Spoon a little bit of the dark chocolate into a piping bag, and spread the rest over the hardened bark.
Spoon all of the white chocolate into a piping bag. While the final layer of chocolate is still warm, start creating ghosts by piping circles of white chocolate. Using a pointy object like a toothpick or a metal skewer, draw one end of each circle out to create a tail.
Using the dark chocolate in the piping bag, add eyes and mouths.
Add some chocolate pearls and refrigerate to harden completely.