1. Heat oven to 350°F. Line bottom of three 8-inch round baking pans with wax paper. Lightly grease sides of pans. Combine flour, cocoa, baking soda and salt; set aside.
2. Place butter in large microwave-safe bowl. Microwave at MEDIUM (50%) 1 minute or until melted; stir in sugar. Add milk, vinegar and vanilla to butter mixture; stir until blended. Add dry ingredients; whisk until well blended. Pour batter evenly into prepared pans.
3. Bake 15 minutes or until wooden pick inserted in center comes out clean. Cool 10 minutes. Remove from pans to wire racks; gently peel off wax paper. Cool completely.
4. Prepare CHOCOLATE MOUSSE FILLING. Place one cake layer on serving plate; spread 2 tablespoons preserves over top. Carefully spread half of filling over preserves to within 1 inch of edge. Refrigerate about 10 minutes. Place second layer on top; repeat procedure with remaining preserves and filling. Place remaining layer on top. Refrigerate while preparing CHOCOLATE GANACHE. Spread ganache over top and side of cake.
5. Refrigerate at least 30 minutes. At serving time, garnish with sweetened whipped cream; sift cocoa over top. Refrigerate leftover cake. 12 servings.
CHOCOLATE MOUSSE FILLING
1 teaspoon unflavored gelatin
1 tablespoon cold water
2 tablespoons boiling water
1/2 cup sugar
1/4 cup HERSHEY'S Cocoa
1 cup (1/2 pt.) cold whipping cream
1 teaspoon vanilla extract
Sprinkle gelatin over cold water in small bowl; let stand 1 minute to soften. Add boiling water; stir until gelatin is completely dissolved and mixture is clear. Cool slightly. In small mixer bowl, stir together sugar and cocoa; add whipping cream and vanilla. Beat at medium speed of mixer, scraping bottom of bowl occasionally, until stiff; pour in gelatin mixture and beat until well blended. Refrigerate about 20 minutes. About 2 cups filling.
CHOCOLATE GANACHE: Heat 1 cup (1/2 pt.) whipping cream in heavy saucepan over low heat until warm. Add 1-1/2 cups HERSHEY'S SPECIAL DARK Chocolate Chips or HERSHEY'S Semi-Sweet Chocolate Chips; stir constantly just until chips are melted and mixture is smooth. Do not let mixture come to a boil. Transfer mixture to medium bowl; refrigerate until of spreading consistency, about 1-1/2 hours. About 1-2/3 cups ganache.