MICROWAVE each package of white chocolate in separate medium microwavable bowl on HIGH 2 minutes or until white chocolate is almost melted, stirring halfway through heating time. Stir until white chocolate is completely melted.
STIR red food coloring into one bowl of melted white chocolate until well blended. Alternately spoon white chocolate and tinted chocolate onto wax paper-lined cookie sheet or tray. Tap cookie sheet on table top to evenly disperse chocolate. Swirl white chocolate with knife several times for marble effect.
REFRIGERATE 1 hour or until firm. Break into pieces.
Storage Know-How: Store in air tight container in refrigerator for several weeks.