Make popcorn according to package directions. In large bowl, microwave peanut butter and brown sugar for 1 minute; stir to combine. Add popcorn and stir until well coated. Sprinkle liberally with nonpareils, stirring to distribute. Spread onto parchment-lined sheet pan.
Melt Candy Melts candy according to package directions. Drizzle over popcorn. Let set at least 10 minutes before serving.