In a large bowl, combine softened butter with peanut butter, and powdered sugar until a thick dough forms.
Fold in m&ms. Roll the mixture into bite-sized balls. Set onto plates, refrigerate for at least 30 minutes. Place the chocolate chips into a microwave-safe bowl, heat in the microwave in 30-second intervals, stirring after each until fully melted and smooth.
Dip each peanut butter ball into the melted chocolate. Set back onto plates, and refrigerate until the chocolate has set.