1. Heat oven to 350°F. Grease and flour two 9-inch round baking pans.
2. Beat butter, sugar, eggs and vanilla in large bowl until blended. Stir together flour, cocoa, baking soda and baking powder; add to butter mixture alternately with milk, blending just until combined. Pour batter into prepared pans.
3. Bake 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool 10 minutes; remove from pans to wire racks. Sprinkle each layer with 1 tablespoon creme de cacao, if desired; cool completely.
4. Meanwhile, prepare CREME DE CACAO FILLING. Split each cake layer horizontally into 2 layers. Place one layer on serving plate; spread with one-third of FILLING. Repeat layering with remaining cake and FILLING, ending with cake layer. Cover tightly; refrigerate at least 8 hours.
5. Prepare CHOCOLATE GANACHE GLAZE; spoon on top of chilled cake, allowing glaze to drizzle down side of cake. Refrigerate. 10 to 12 servings.
CREME DE CACAO FILLING: Beat 1 cup (1/2 pt.) cold whipping cream, 2 tablespoons creme de cacao (optional) and 1 tablespoon HERSHEY'S Cocoa in small bowl until stiff. Cover; refrigerate. About 2 cups.
CHOCOLATE GANACHE GLAZE
1 HERSHEY'S SPECIAL DARK Chocolate Bar (6.8 oz.), broken
1/4 cup whipping cream
1 tablespoon butter
1-1/2 teaspoons creme de cacao (chocolate-flavored liqueur) or
Combine chocolate bar pieces, whipping cream and butter in medium saucepan; cook over low heat, stirring constantly, until chocolate is melted and mixture is smooth. Stir in creme de cacao. Cool to lukewarm (glaze will be slightly thickened). About 1 cup.