Line 15x10x1-inch baking pan with waxed paper, leaving 2 inches extending over each end. Chill in freezer. Spread chocolate ice cream evenly in chilled waxed paper-lined pan. Freeze about 3 hours or until firm.
Spread mint ice cream evenly over chocolate ice cream. Freeze 3 hours or until firm but not solid. (If ice cream freezes solid it will crack when rolled.)
To remove ice cream from pan, lift paper ends; place on flat surface. To roll, loosen long sides of ice cream from paper. Working quickly, lift short end of paper and turn over end of ice cream, pressing with fingers to start roll. Roll up jelly-roll fashion, peeling paper back and continuing to lift paper and roll ice cream to end. Discard paper. Place ice cream roll, seam side down, on freezerproof platter. Freeze 2 hours or until firm. To serve, cut into slices.