In a double boiler insert, add white chocolate and 1/4 c. of cream.
Fill a 2.5-qt. sauce pan with 1/3 water and heat to just simmering. Place double boiler insert over simmering water and stir the white chocolate and cream until chocolate is melted.
Set up a second double boiler and add dark chocolate and 1/2 c. cream to the insert over simmering water. Combine until smooth.
Swirl white chocolate mixture into dark chocolate mixture. Enjoy with fresh fruit and cake.