1. Line 1-1/2-L glass bowl with plastic wrap. Spoon sorbet into prepared bowl; press firmly onto bottom of bowl with back of spoon. Cover with 1/2 cup crumbs.
2. Repeat layers twice, substituting the chocolate, then vanilla ice cream for the sorbet. Freeze 4 hours.
3. Use plastic wrap to remove dessert from bowl just before serving. Invert onto plate. Remove and discard plastic wrap.
4. Frost dessert with Cool Whip; sprinkle with coconut. Cut into wedges to serve.