1. Heat oven to 350°F. Line muffin cups (2-1/2 inches in diameter) with paper bake cups.
2. Stir together flour, sugar, baking soda and salt in large bowl. Add water, oil, vinegar and vanilla; beat with whisk or spoon until batter is smooth. Blend in melted chocolate. Fill muffin cups 2/3 full with batter.
3. Bake 16 to 18 minutes or until wooden pick inserted in center of cupcakes comes out clean. Remove from pan to wire rack. Cool completely. Frost cupcakes with CHOCOLATE FROSTING. 12 cupcakes.
3 tablespoons butter or margarine, softened
1 cup powdered sugar
1/4 cup HERSHEY'S Cocoa
2 to 3 tablespoons milk
1/2 teaspoon vanilla extract
Beat butter in small bowl. Add powdered sugar and cocoa alternately with milk, beating to spreading consistency. Stir in vanilla. About 1 cup frosting.