Line cookie sheet with waxed paper, letting paper hang over the sides. Melt semisweet chocolate morsels **RESERVING 1/4 cup chocolate morsels for topping ** in microwave for 2 minutes, stirring every 30 seconds, or until smooth.
Pour chocolate onto prepared cookie sheet, spreading to cover entire surface, forming 1 even layer.
Melt white morsels **RESERVING 1/4 cup white morsels for topping** in microwave for 2 minutes, stirring every 30 seconds, or until smooth.
Drizzle melted white chocolate over semisweet chocolate layer. Using a toothpick, swirl the melted chocolates together, making a marbled effect.
Sprinkle nuts and remaining semisweet and white morsels over chocolate. Gently press into melted chocolates.
Refrigerate for at least 30 minutes, so chocolate is firm. Remove waxed paper from chocolate. Then cut or break chocolate into bite-size pieces.