In a large bowl, beat peanut butter and butter with a mixer at medium speed until smooth.
Slowly beat in confectioners' sugar. Then stir in the cereal.
Roll mixture into 1-inch balls and place on a baking sheet lined with wax paper or parchment paper.
Melt the chocolate according to the directions on the package.
Use a fork to dip each ball in the melted chocolate coating. Let the excess drip off, and gently place each peanut butter ball on the prepared baking sheet.
Sprinkle with chopped peanuts, if desired. Freeze for 15-20 minutes or until the chocolate coating is firm.
Remove from the pan and store in an airtight food storage container for up to 1 week.