1. Preheat oven to 350°F. Grease and flour two 9-inch round cake pans.
2. Prepare, bake and cool cake as directed on package for basic recipe.
3. For chocolate hearts garnish, spread melted chocolate to 1/8-inch thickness on waxed-paper-lined baking sheet. Cut shapes with heart cookie cutter when chocolate begins to set. Refrigerate until firm. Push out heart shapes. Set aside.
4. To assemble, split each cake layer in half horizontally. Place one split cake layer on serving plate. Spread one third of whipped topping on top. Repeat with remaining layers and whipped topping, leaving top plain. Frost sides and top with frosting. Sprinkle pistachios on top. Position chocolate hearts by pushing points down into cake. Refrigerate until ready to serve.
Chocolate Strawberry Dream Torte
Omit semisweet chocolate chips and chopped pistachios. Proceed as directed through step 2. Fold 1-1/2 cups chopped fresh strawberries into whipped topping in large bowl. Assemble as directed, filling torte with strawberry mixture. Frost with milk chocolate frosting, and garnish cake with strawberry fans and mint leaves, if desired.