To make the bottom PURPLE layer, add 6 ounces of chopped white chocolate to one bowl of the sweetened condensed milk. Microwave uncovered on High 1 minute; stir until smooth. Stir in 1/4 teaspoon vanilla. Tint PURPLE by adding 9 drops of red food color and 6 drops of blue food color; stir well. Immediately pour fudge mixture in the bottom of a foil lined pan, spreading to edges. Firmly tap pan on counter to even out layer. Place in freezer for at least 15 minutes or until top appears set.