1. Heat oven to 350°F. Grease 13x9x2-inch baking pan.
2. Combine flour, sugar, cocoa, butter, water, eggs, baking powder, baking soda and vanilla in large bowl; beat until smooth. Pour into prepared pan.
3. Bake 25 to 30 minutes or until wooden pick inserted in center comes out clean. Cool completely in pan on wire rack. Frost with EASY ORANGE FROSTING. Drizzle with CHOCOLATE DRIZZLE. 12 to 16 servings.
EASY ORANGE FROSTING: Stir together 1 container (16 oz.) vanilla ready-to-spread frosting, 1/2 teaspoon orange extract, 1/8 teaspoon freshly grated orange peel and 1 or 2 drops each of red and yellow food color, if desired.
CHOCOLATE DRIZZLE: Place 1/4 cup HERSHEY'S SPECIAL DARK Chocolate Chips or HERSHEY'S Semi-Sweet Chocolate Chips and 1-1/2 teaspoons shortening (do not use butter, margarine, spread or oil) in small microwave-safe bowl. Microwave at MEDIUM (50%) 15 to 30 seconds; stir. If necessary, microwave at MEDIUM an additional 10 seconds at a time, stirring after each heating, just until chips are melted and mixture is smooth.