PREHEAT oven to 375°F. Remove 36 of the pecan halves; set aside. Finely chop remaining pecans; set aside. Mix cereal, molasses and egg until well blended; let stand 5 minutes. Mix flour, baking soda and spices in separate bowl; set aside.

BEAT margarine and 3/4 cup of the sugar in large bowl until light and fluffy. Add cereal mixture; mix well. Stir in flour mixture until well blended. Add chopped pecans; mix well. Shape into 36 balls, each about 1 inch in diameter; roll in remaining 1/4 cup sugar until evenly coated. Place, 2 inches apart, on lightly greased baking sheets. Flatten balls with bottom of glass. Insert 1 whole pecan into top edge of dough round for the "pumpkin's stem."

BAKE 7 to 9 minutes or until cookies feel set to the touch. Let stand 1 minute; remove to wire racks. Cool completely. Spread each cookie with 1 tsp. of the Powdered Sugar Icing. Decorate with candy corn, using about 3 pieces on each cookie. Let stand until icing is set.