Preheat oven to 350°F. Combine flour, cocoa, baking soda and salt in medium bowl. Beat sugar and butter in large bowl with electric mixer at medium speed until light and fluffy. Add corn syrup, egg and vanilla; beat until well blended. Gradually beat in flour mixture at low speed until blended. Cover and refrigerate dough about 15 minutes or until firm.

Shape dough by tablespoonfuls into 1-inch balls; place 2 inches apart on ungreased cookie sheets. Flatten slightly with fingers. Bake 10 to 12 minutes or until cookies are set. Immediately transfer to wire racks; cool completely.

Soften ice cream at room temperature about 10 minutes or in microwave oven on MEDIUM (50%) 10 to 20 seconds. For each ice cream sandwich, place about 1/4 cup (1 small scoop) ice cream on flat side of one cookie; top with another cookie, flat side down. Press gently so that ice cream meets edges of cookies. Immediately roll edges of ice cream in decorations, if desired. Wrap in plastic wrap; freeze until ready to serve.