Have ready several large baking sheets lined with parchment paper.
In a large bowl, using an electric mixer on low speed or by hand, combine the confectioners' sugar, peanut butter and butter until well blended. Add the puffed rice cereal and mix well. Using your hands, form the mixture into walnut-size balls (about 1 generous tablespoon each) and place them on a tray. Cover and refrigerate for about 1 hour, or until firm.
Melt the chocolates in a bowl set over a saucepan of barely boiling water or in the microwave. Add the oil and stir until smooth. Using a fork and working with 1 chilled peanut butter ball at a time, dip the balls into the melted chocolate mixture, rolling to coat evenly. Shake off any excess chocolate and transfer to the lined baking sheets. Set aside for at least 2 hours to set.
The peanut butter balls can sit for as long as 8 hours at room temperature before serving. Refrigerate in an airtight container for up to 2 weeks.
A variation I found that looks yummy as well!
2 c. crushed graham crackers
2 c. powdered sugar
2 c. peanut butter (creamy or chunky, your choice)
1/4 c. butter (barely melted in the microwave)
Mix together the first 4 ingredients as you would a pie crust. Chill in the fridge for at least 1 hour.
Melt the dipping chocolate. Roll peanut butter mixture into small balls, and dip into the chocolate. Allow to set on wax paper. Chill until served.