1/2 cup chocolate syrup
1/3 cup semisweet chocolate chips
2 cups crisp rice cereal
1/4 cup sour cream
1 quart chocolate chip ice cream, softened
Coat bottom and sides of an 8-inch plate with butter. Combine chocolate syrup and chips in a small microwave safe bowl. Microwave on HIGH until hot, about 45 seconds. Stir until smooth. Set aside 1/3 cup of the chocolate mixture.
Combine remaining chocolate mixture with cereal and mix to coat the cereal. Press into prepared pie plate. Freeze until firm (about 15 minutes).
Combine reserved chocolate with the sour cream and mix well. Spread 1/2 of ice cream over cereal mixture. Drizzle with 1/2 the chocolate/sour cream mixture. Top with remaining ice cream and drizzle with chocolate/sour cream. Freeze, covered until firm (about 1 hour).