Coat bottom & sides of 8-inch pie plate with vegetable spray. Combine chocolate syrup and chocolate chips in small microwavable bowl. Microwave on HIGH until hot, about 45 seconds. Stir until smooth. Reserve 1/4 cup.
Combine remaining mixture and cereal in medium bowl and mix to coat cereal. Press mixture over bottom & up sides of prepared pie plate. Freeze until firm, about 15 minutes.
Combine reserved chocolate mix and the sour cream in a small bowl and mix well. Spread half the ice cream into pie plate. Drizzle with half the sour cream mix. Top with remaining ice cream & drizzle with remaining sour cream mix. Freeze pie, covered, until firm, about 1 hour.