In small bowl, stir together melted white chocolate and green food coloring. Dip each TWIX® into bowl, shaking excess chocolate back into bowl.
Transfer to parchment paper–lined tray. Place pretzel stick halves on each side of TWIX® in lower third of bar to resemble Frankenstein’s bolts. Sprinkle tops of each TWIX® with cookie crumbs to resemble hair. Let stand for at least 1 hour or until chocolate is set.
Scrape melted dark chocolate into piping bag fitted with small round tip. Pipe 2 dots onto each TWIX®; press candy eyes onto dots. Drizzle melted chocolate in crooked line for mouth.