Layer the bottom of an 8" round springform pan with 1-1/4 cup of the macaroons. Spread chocolate ice cream evenly over the crumbs. Sprinkle 4 of the crushed Heath bars over the ice cream. Dribble 3 tbls of the chocolate syrup and 2 tbls of the Kahlua over chocolate ice cream. Cover with remaining macaroons. Top evenly with vanilla ice cream. Sprinkle remaining crushed Heath bars over ice cream, then the chocolate syrup and Kahlua. Cover and freeze for at least 8 hours or overnught. When ready to serve, run the blade of a kitchen knife around the edges of the pan, remove the sides and place the ice cream cake on a serving paltter. Slice and serve. TIP: Place Heath bars in freezer till frozen. They are then easily broken with a mallet. VARIATIONS: Other cookies, such as chocolate wafers or vanilla cookies can be used instead of macaroons. Different variations of chocolate ice crem, such as chocolate-almond or others can be used.