In medium saucepan, combine sugar and corn starch. Gradually stir in milk. Cook and stir over medium heat until mixture just comes to boil. Reduce heat and cook 1 minute longer. Gradually whisk hot milk mixture into beaten egg. Divide mixture in half. Stir white chocolate into one half and semi-sweet chocolate into the other. Cover surface of fillings directly with plastic warp. Chill.
Meanwhile, prepare puff pastry shells according to package directions.
To serve, spoon white and semi-sweet chocolate fillings into shells. Swirl with knife to marble. Dust each serving with cocoa powder.
Makes 6 servings.
*Note: If you like, substitute 1 package mini puff pastry shells. Divide white and semi-sweet chocolate fillings evenly among mini shells.
Date: June 9, 2003