Coat bottom and sides of a 8-inch pie plate lightly with butter..
Combine chocolate syrup with chocolate chips in a small microwave-safe bowl. Microwave on high until hot,about 45 seconds.Stir until smooth.Reserve 1/4 c. of the chocolate mixture.
Combine remaining chocolate mixture and cereal in a medium bowl and mix to coat cereal. Press mixture over bottom and sides of prepared pie plate.Freeze until firm,about 15 minutes.
Combine reserved chocolate mixture and the sour cream in a small bowl and mix well.Spread half the ice cream in the prepared pie plate.Drizzle with half the sour cream mixture.Top with remaining ice cream and drizzle with remaining sour cream mixture.Freeze pie,covered,until firm,about 1 hour.
NOTE: To get clean,even slices of pie.Fill a bowl with hot water.Make a cut,then dip a knife into the hot water then wipe it off..The hot knife slices right through the frozen ice cream and crust with little effort.That makes it easier to cut pie into 8 slices..