1. Beat butter, sugar, egg and vanilla in large bowl until creamy. Stir together flour, cocoa and baking powder; add alternately with milk to butter mixture, beating until well blended. Divide dough into quarters. Shape each quarter into ball; flatten slightly. Wrap individually in plastic wrap. Refrigerate 1 to 2 hours or until firm enough to handle.
2. Meanwhile, break chocolate bar into pieces on scored lines; cut each piece in half.
3. Heat oven to 350°F. Working with one portion of dough at a time, on floured surface, roll to about 1/8-inch thickness. Using 2-inch round cookie cutter, cut dough into even number of rounds. Place half the rounds on ungreased cookie sheet. Place one chocolate piece in center of each round. Place remaining rounds on top. Using tines of fork, seal edges.
4. Bake 8 minutes or until set. Remove from cookie sheet to wire rack. Cool completely. Decorate top of cookies with icing to resemble pumpkin face. Makes about 40 cookies.
VANILLA DRIZZLED SURPRISE COOKIES: Omit orange decorating icing. Decorate top of cookies with VANILLA DRIZZLE (recipe follows).
VANILLA DRIZZLE: Place 1/4 cup HERSHEY'S Premier White Chips and 1/2 teaspoon shortening (do not use butter, margarine, spread or oil) in small microwave-safe bowl. Microwave at MEDIUM (50%) 30 seconds; stir. If necessary, microwave at MEDIUM an additional 15 seconds at a time, stirring after each heating, just until chips are melted.
VANILLA COOKIES: Omit cocoa; use 2-1/4 cups all-purpose flour. Decorate with SYMPHONY DRIZZLE (recipe follows).
SYMPHONY DRIZZLE: Omit Premier White Chips; use half of 7 oz. HERSHEY'S SYMPHONY Milk Chocolate Bar and 1/2 teaspoon shortening. Follow microwave directions for VANILLA DRIZZLE.