1) Place the cereal in a large bowl
2) In a small saucepan, combine the chocolate and peanut butter. Cook over low heat, stirring, until the chocolate melts and the mixture is smooth, about 2 minutes
3) Add the chocolate–peanut butter mixture to the cereal and mix to coat. Spread the cereal mixture onto the bottom and 1 1/2 in. up the sides of a 9-in. springform pan. Freeze until set, about 10 minutes.
4) Let the ice cream soften at room temperature just until spreadable, about 10 minutes. Spread ice cream evenly into the chilled crust and freeze until firm, at least 4 hours and up to 2 days.