1Arrange 16 of the graham crackers in bottom of ungreased jelly roll pan, 15 1/2x10 1/2x1 inch. Spread frosting on top of each cracker. Spread marshmallow creme on one side of remaining crackers.
2Cut ice cream crosswise into four 3/4-inch-thick slices. Cut each slice into fourths to make 16 pieces. (Freeze remaining ice cream for another use.) Place one ice cream piece on each cracker in pan. Top with remaining crackers, marshmallow sides down, pressing lightly.
3Cover and freeze about 2 hours or until firm. Wrap each sandwich in foil or plastic wrap; store in freezer.