Preheat oven to 375°F. Spray Jack-O-Lantern mini mold cavities with vegetable pan spray; set aside.
In large bowl, cream butter and sugar with electric mixer until light and fluffy. Beat in egg and vanilla; mix well. Stir in melted chocolate. Combine flour and baking powder; gradually add to butter mixture, beating until smooth. Press a heaping tablespoon cookie dough into prepared cavities (dough should be about 1/4-inch thick).
Bake 15 to18 minutes or until edges are set (centers will be soft). Cool in mold on cooling grid 20 minutes; remove from mold and cool completely.
Meanwhile, combine icing with orange zest in medium bowl. Add orange icing color to achieve desired color. When cookies are completely cooled, spread icing onto flat side of one cookie. Top with second cookie.